Biodiversity net gain: nationally significant infrastructure projects

When BNG applies to NSIPs

From 2 November 2026, biodiversity net gain (BNG) will be mandatory for nationally significant infrastructure projects (NSIPs) in England. NSIP developers who apply for a development consent order (DCO) on or after this date need to deliver at least 10% net gain in biodiversity.

The statutory framework for mandatory BNG for NSIPs is introduced by Schedule 15 to the Environment Act 2021, which inserts Schedule 2A into the Planning Act 2008.

Mandatory BNG applies to NSIPs, or components of NSIPs, as far as the mean low-water mark, including the intertidal zone but not the marine environment beyond it.

Mandatory BNG does not apply to infrastructure consented through other routes, like Hybrid Bills.

Projects that cross England’s borders

Some NSIPs may cross England’s borders. The BNG baseline, BNG boundary plan and BNG metric calculation must only include habitats in England. Any biodiversity enhancements and creation that you intend to count towards your BNG must be delivered in England.

If you voluntarily choose to deliver BNG for any part of the project outside of England, you must calculate it separately. This will make it clear how the project will deliver mandatory BNG in England.

Follow the relevant biodiversity gain statement

In June 2026, Defra published biodiversity gain statements for NSIPs. These explain how NSIPs need to calculate, deliver and report on BNG. They have the same effect as if they were included in the relevant national policy statement (NPS). The gain statements will be incorporated into the relevant NPS when each NPS is next reviewed.

You must follow the biodiversity gain statement relevant to your project to receive development consent. This guidance is supplementary to the gain statements and includes further information and best practice.

You will deliver BNG alongside existing environmental policies and obligations. BNG does not change or replace them.

The mitigation hierarchy

You should apply the mitigation hierarchy alongside BNG. This means avoiding significant harm to biodiversity in the first instance. Where this is not possible, you should minimise losses. As a last resort, you must provide compensation for any harm to biodiversity.

This is set out in the gain statements.

Check how BNG applies to irreplaceable habitat

You must follow the requirements set out in the relevant gain statement in relation to irreplaceable habitat.

There is further guidance on how to treat irreplaceable habitat for BNG in support of these statements.

Measure biodiversity value

For the purposes of BNG, biodiversity value is measured in standardised biodiversity units.

A habitat will contain a number of biodiversity units, depending on things like its: 

• size
• condition
• location
• type

To calculate the number of biodiversity units to achieve BNG, you must use the statutory biodiversity metric tool.

You must provide a single metric calculation for your development as part of your DCO application. This applies even where parts of the NSIP are not physically connected or are located in different local planning authority (LPA) areas. For example, where there is associated infrastructure or construction compounds separate from the main development.

This is also valid for phased development.

BNG baseline

Using the metric tools and guides, you will need to calculate the biodiversity value of on-site habitats before development. This is called the BNG baseline.

The area on which you calculate the baseline is called the BNG boundary. This may not be the same as the development’s order limits. The order limits are the geographic limits of the powers the applicant is seeking through the DCO.

As the site layout develops during the design process, your BNG boundary may change. In that case, you will need to update your baseline.

What habitats to include in your BNG baseline

Your baseline calculation must include the pre-development biodiversity value of any habitats within your order limits that will be:

• negatively impacted by the development
• used to contribute towards the development’s BNG

Habitats negatively impacted by the development

Your baseline must include all habitats within your order limits that will be negatively impacted by the development.

Your ecologist should advise on any expected negative impacts to habitats. This includes all habitats subject to permanent or temporary:

• loss – for example, permanent loss due to development or temporary loss during construction

• deterioration of habitat condition (based on the biodiversity metric condition assessment) – for example, from shading or disturbance caused by the development

You must consider all expected impacts, including those from:

• development
• enabling and site preparation works
• construction activity, including direct habitat clearance, temporary compounds, storage areas and access routes
• associated development included within the DCO application
• expected impacts during the maintenance and operation of the development

On Statutory biodiversity metric tools and guides, you can find out how to:

• conduct the habitat condition assessment – use the biodiversity metric condition assessments spreadsheet
• record a deterioration in habitat condition – read the statutory biodiversity metric user guide

Impacted habitats that can count as retained

You can count habitats that are impacted temporarily as ‘retained’ in your baseline if you reinstate them to their original habitat type and condition:

• within 5 years of the date the initial impact happened – for impacts on low or very low distinctiveness habitat
• within 2 years of the date the initial impact happened – for impacts on medium distinctiveness habitat

If these conditions apply, you must still include these negatively impacted habitats in your calculation. However, you do not need to record them as lost. This reduces the number of biodiversity units you will need to provide for that habitat type.

The 2- or 5-year period starts from the date the particular habitat area is impacted. The date of impact, and therefore the end of the 2- or 5-year period, may vary for different habitat areas across the site.

There is more detail on accounting for temporary losses in the metric user guide.

If you intend to reinstate an impacted habitat within 2 or 5 years so that it can be counted as retained in the metric, but are subsequently unable to achieve this, you can no longer count it as retained. You must reflect this in your updated biodiversity metric and updated or phase gain plans.

Habitats used to contribute towards BNG

As well as all negatively impacted habitats, your baseline calculation must include the pre-development biodiversity value of any habitats within the order limits that will be used to contribute towards BNG.

You should include any habitats where on-site biodiversity gains will be located. These are any habitats:

• on which you plan to enhance or create new habitats
• that count towards the post-development biodiversity value

You should include any habitats regardless of whether the habitat creation or enhancement is:

• only for the purpose of BNG
• carried out for other purposes and you intend it to count towards BNG outcomes in part or full – for example, Environmental Impact Assessment mitigation or green infrastructure

To find out when habitat created or enhanced as part of your development for other purposes can also be used for BNG, read the guidance on what you can count towards a development’s BNG.

If your project design details are uncertain

If the final project location or construction area is not fixed, NSIPs can include areas of design uncertainty or limits of deviation. You should determine the habitats to include in your baseline using professional judgement and the information available when you prepare your outline gain plan.

In your outline gain plan, you should describe:

• the assumptions you have made

• how you would address habitat impacts if an alternative realistic route is chosen

If you have uncertainty on the extent of habitat impacts

If you do not know the final extent of habitat impacts, your baseline must reflect the realistic worst-case extent of habitat loss or deterioration. This means using the maximum design and construction parameters for your project, rather than a hypothetical or overly precautionary scenario.

For example, for a linear scheme, you should use the maximum construction working width rather than the full width of the limits of deviation.

If you have uncertainty on the location of habitat impacts

Depending on the final location of your development within your order limits, you might impact habitats of different value, condition or distinctiveness. The approach you take to your baseline will depend on whether you have a most-likely route or design option, or not.

If you have a strongly preferred or most-likely route or design option, you should calculate your baseline using your realistic worst-case extent and that design option.

If you do not have a most-likely route, you should take a precautionary approach. You should assume impacts to the highest-value habitats that could realistically be affected unless you have mitigation, design measures or construction controls to avoid those impacts.

Unimpacted habitats

You can exclude unimpacted habitats from your baseline. You should only exclude these habitats if your ecologist can confirm that there are no expected impacts to them from the development. This includes permanent loss, temporary loss, or deterioration in condition.

You can also choose to include unimpacted habitats in your baseline. You might do this to:

• simplify mapping and evidence
• demonstrate the net gain across a larger area

If there are small parcels of unimpacted habitats, you should consider including them in your baseline. This will make your baseline more proportionate, easier to interpret, and simpler to evidence.

If you choose to include any unimpacted habitats in the baseline, they will be subject to the 10% BNG objective. These habitats will be included in the post-development biodiversity value and will count towards BNG.

Where infrastructure will be located above or below ground, the habitat beneath or above is usually included within the order limits. However, this habitat might remain unimpacted.

Below-ground infrastructure

For below-ground infrastructure or construction techniques, your baseline can exclude habitats above the works if you are certain they will not be impacted or degraded.

For example, if you use below-ground horizontal directional drilling, you may exclude areas of unimpacted habitat above the drilling area. You must include any habitats that will be impacted, for example during access, set up and working around the drilling access points.

Your ecologist should confirm that your working methods and impact avoidance measures will result in no impact to any areas you exclude from your baseline. They should consider the type of habitats present and the proposed disturbance depth.

Above-ground infrastructure

Your baseline can exclude areas of habitat beneath or immediately next to an above-ground structure if you are certain they will not be impacted or degraded.

For example, you can exclude habitats in the order limits beneath overhead electricity lines if you are sure they will remain unimpacted by the development. You must still include any habitats that will be impacted by site preparation or construction activity, such as habitats around pylons, access routes, or temporary storage areas.

Your ecologist should confirm that above-ground infrastructure will not negatively impact any habitats excluded from your baseline.

Survey data and baseline date

Get a professional to do a habitat survey

You should consult an ecologist with appropriate training and experience in habitat identification, creation and management.

They will need to survey the habitat before development and record the data needed for the metric calculation.

The baseline date

The baseline must use information that reflects the value of habitats on the date you submit your outline biodiversity gain plan.

The gain statements set out the requirements for the habitat survey, including:

• appropriate timing, validity and updating of survey data
• use of older surveys

You should consider using an earlier date in the following circumstances:

• where unauthorised loss or impact to the biodiversity value of on-site habitat (‘degradation’) happened before you submitted the DCO application
• if activities carried out under an existing planning permission or DCO that has not begun or has not been completed result in a lower biodiversity value of the on-site habitat than it would otherwise have been – for example, if a site is cleared under an existing planning permission, but the development is not built

The earlier date should be immediately before the degradation activities were carried out, or the closest date before this for which you have accurate data. This is to discourage the wilful degradation of existing on-site habitats to reduce the pre-development biodiversity value.

You should discuss the need for an earlier baseline date with the Planning Inspectorate as early as possible. The ‘examining authority’ (the inspectors who review your application) and the Secretary of State will then need to agree on your earlier baseline during the consent phase.

If you use an earlier date, you must have surveys or other evidence that show you meet these circumstances.

You do not need to:

• account for any degradation before 30 January 2020
• prove the absence of degradation since that date when submitting your DCO application

Making sure the survey data is accurate

Habitats on a site may change naturally over time or due to a change in habitat management. You need to consider whether the survey data is still relevant at the time you submit your outline biodiversity gain plan.

You will need to resurvey your site depending on:

• whether the habitat type or condition is likely to have changed since your survey date
• how long it has been since the date of your previous surveys
• whether there have been any changes in the uses or management of the site

Your ecologist should help you understand if you need to update the surveys of your site. You should inform them if you know of any changes to the land use or management of the site.

Where survey data is unavailable

It may not be possible to access parts of the site or obtain accurate survey data, for example due to degradation. Where you do not have accurate data, you must calculate your baseline using any evidence or data available – for example, previous site surveys, online data sources and aerial imagery.

You should apply the highest-value type and condition of habitats that are likely to have been or be present on the site, based on available evidence.

Developing on an existing gain site

You must check if your development will impact:

• a site that is already registered on the national biodiversity gain sites register
• any significant on-site gains that have been legally secured through another planning permission or DCO

Considering BNG at an early stage in site selection and design can help you avoid impacting existing gain sites.

Where you cannot avoid impacts due to site constraints, you must calculate your baseline using the habitat type and condition the existing gain site is planned to achieve by the end of the 30-year management period.

The register lists all planned habitat for every registered gain site. You can use this information in your baseline calculation if your development impacts the entire registered gain site.

If your development impacts only part of a registered site, you will need to determine which planned habitats are within your BNG boundary. To work this out, you should take the following actions:

• contact the owner, relevant LPA or responsible body of the site for detailed maps of planned habitats
• check the BNG documents for the development the registered gains are allocated to

If you cannot obtain this, you should agree a proportionate approach with the decision maker considering the available evidence.

If significant on-site gains secured to another development are being impacted, you could look for the biodiversity gain plan or a habitat management and monitoring plan (HMMP) for that development on:

• the local planning portal – for developments with planning permission
• the Planning Inspectorate NSIP portal – for NSIPs

If you cannot find detailed information in these sources, the relevant LPA where the site is located or the Planning Inspectorate may have this information.

If your development will impact existing gain sites, you may need to amend, compensate for or take on the legal agreements that are already in place. You should discuss this as early as possible with the signatories to the legal agreement and seek your own legal advice. The same measures apply if your development is on land that is already subject to other environmental or biodiversity-related legal obligations.

How to deliver BNG

There are 3 ways you can achieve your 10% BNG.

For NSIPs, you can consider options 1 and 2 at the same time.

1. On-site gains

You can enhance and restore biodiversity on-site. For NSIPs, on-site means any areas within the BNG boundary.

All on-site habitat creation or enhancement is considered to be significant. You will need to consider early that significant on-site gains must be maintained and secured for 30 years.

Any habitat within the BNG boundary that you retain or will reinstate is considered non-significant. You do not need to secure it and can count towards your BNG. Reinstated habitats must be recreated to their original type and condition.

2. Off-site gains

For NSIPs, off-site means any habitat outside of the BNG boundary.

Any habitat within the order limits used for BNG purposes must be included in the BNG boundary. This means off-site habitats will also be outside the order limits.

You can make off-site gains by either:

• creating off-site units on other land you own
• buying off-site units from landowners on the off-site BNG market

Creating off-site gains on other land you own

If you own land outside your order limits, you can use it to enhance or create habitats. These can be allocated to your site.

To do this, you must follow the guidance for land managers for creating off-site habitats, including:

• securing the gains with a 30-year legal agreement
• registering the site on the biodiversity gain sites register
• allocating the site to your development

3. Statutory biodiversity credits

This is a last resort option after you have exhausted all on-site and off-site opportunities.

If you want to buy statutory biodiversity credits, you must prove why you cannot meet BNG using on-site and off-site options.

Other work you can count as part of your BNG

If you need to create or enhance habitats as part of your development for other purposes, you may be able to count all or part of this towards your BNG.

There is more information available on what you can count towards a development’s BNG.

Plan your BNG delivery

You should consider BNG early as part of the overall project design. You will need to consider BNG alongside other environmental and planning requirements, as well as future uses of the site.

Each NSIP will have different constraints and opportunities that will determine how BNG can be delivered. The balance between delivering BNG on-site and off-site will vary between projects.

Design your BNG enhancement and creation

By taking an iterative approach and using the metric tool to test different design options, you can:

• find the most efficient design that reduces negative impacts and avoids impacts to higher value habitats, where possible
• refine your BNG design as wider project considerations become clearer
• identify smart uses of BNG that can help to deliver other design benefits – for example, infrastructure resilience, social benefit, delivery of other environmental obligations and habitat connectivity

The most appropriate approach to delivering BNG will depend on a combination of factors including:

• site characteristics
• environmental context
• project design and maintenance
• wider project objectives – for example, climate resilience or the benefits to local communities

Ecological considerations

When designing any habitat creation and enhancement, you should make sure they are based on solid ecological expertise. They should take account of the ecological context of the change.

Consider whether:

• the proposals are appropriate considering the use of the site, and the site surroundings – for example, if the habitat can withstand the expected levels of use where there is public access
• the proposals will still be appropriate in 30 years’ time
• soil conditions are suitable for your plans
• plant species or habitat are suitable for the local area
• there are light level or shade constraints
• there will be suitable access to carry out management works – for example, for equipment such as mowers and hedge trimmers

You should also take into account the following conditions which could impact on your BNG plans, and consider how these might change over the 30-year management period for any significant gains:

• climate resilience
• geology and topography
• agricultural land status
• contaminated land
• hydrology and drainage
• flood risk zones
• landscape character and designations
• biosecurity
• invasive plant species

These factors may influence:

• the habitat type and condition that you can realistically achieve
• the management required to establish and maintain it over time

Further details on how you can define and assess habitat condition are in the statutory biodiversity metric condition assessment sheets.

Deliver gains close to your development

Biodiversity gains may be delivered anywhere in England. You are incentivised to deliver on-site gains, or off-site gains close to your development. The metric tool applies a ‘spatial risk multiplier’ penalty to off-site gains that are located away from the development.

The spatial risk multiplier uses different boundaries depending on the type of biodiversity unit:

• LPA and National Character Area (NCA) boundaries for area habitat units and hedgerow units
• Marine Plan Area (MPA) boundaries for intertidal units
• waterbody and operational catchment boundaries for watercourse units

Off-site gains delivered in the same LPA, NCA or MPA boundary that your development is within do not incur a penalty and keep their full value.

Your BNG boundary may fall within multiple LPAs, NCAs or MPAs. In these cases, the multiplier is applied based on the entire BNG boundary, not on particular areas within it. This means you can allocate off-site gains from any of the LPA, NCA or MPA areas your BNG boundary spans without incurring a spatial risk multiplier penalty.

For off-site gains delivered further away in a neighbouring LPA, NCA or MPA, a penalty will apply. This will increase the amount of habitat required to achieve the same amount of biodiversity units. If off-site gains are delivered beyond these neighbouring areas, an even greater penalty will apply.

Deliver watercourse gains

Different rules apply to watercourse units. For watercourse units, the spatial risk multiplier is based on the specific waterbody catchment where the biodiversity loss occurs. This applies even when your BNG boundary crosses multiple waterbody catchments.

To incur no penalty, and keep their full value, you must deliver off-site watercourse gains within the same waterbody catchment where the biodiversity loss occurs.

A penalty will apply for off-site watercourse gains delivered outside the waterbody catchment but within the same operational catchment as the biodiversity loss. This will increase the amount of habitat required to achieve the same amount of biodiversity units. If off-site gains are delivered outside the operational catchment where the biodiversity loss occurs, an even greater penalty will apply.

Consider strategically important locations for gains

Biodiversity gains delivered as part of NSIPs can offer significant opportunities to help deliver wider nature recovery objectives in local areas, and contribute to benefits like:

• habitat corridors that link existing areas of separated habitats – this could include existing or proposed gain sites
• extending, buffering or linking existing statutory or non-statutory wildlife sites
• supporting natural flood management
• contributing to climate mitigation or adaptation

You should consider relevant local nature recovery strategies. These show proposals for nature recovery in locations where they will have the greatest impact (‘mapped measures’).

Through the metric tool, you can apply the strategic significance multiplier if you carry out habitat creation or enhancement that contributes to mapped measures. This incentivises the delivery of mapped measures as it increases the number of units generated. The metric user guide has detailed information on assigning strategic significance.

Timing of BNG delivery

If your project has long construction timescales or a phased delivery, you should consider when you plan to:

• carry out habitat clearance on-site
• deliver your biodiversity gains

The metric incentivises the delivery of habitat as early as possible, including before construction. It accounts for the time difference between biodiversity losses and compensation habitats being created or enhanced through the ‘advance or delay adjustment’. This adjustment can increase or decrease the biodiversity units you achieve.

Delivering habitats earlier can increase the units generated from the same habitat creation. This may be particularly relevant for linear or large phased projects where you may be able to deliver habitats early in parts of the site that will not be affected by construction activities.

Protected sites and species

BNG does not change existing policy on protected sites and species.

If you are creating or enhancing habitats on a protected site or with protected species, you may be able to count it towards your BNG.

Consider aerodrome safeguarding

Aircraft can be vulnerable to bird strike. This can pose a significant risk to aviation safety. There is usually a bird strike consultation zone around aerodromes. This can extend up to 13 kilometres from the aerodrome. If you plan to deliver BNG within a bird strike consultation zone, you must design and manage your habitats to avoid attracting birds that could increase the strike risk.

You should engage early with the relevant safeguarding authorities before you submit your DCO application. Relevant authorities may include:

• the aerodrome operator
• the Secretary of State for Defence – for military aerodromes
• the Civil Aviation Authority

In your designs, you should:

• demonstrate your BNG will not result in an unacceptable increase in bird strike risk
• include appropriate avoidance, mitigation and long-term management measures

Considering safeguards early in your design process will help reduce the risk of issues arising during the project examination stage.

The Civil Aviation Authority provides further guidance on wildlife hazard management.

Calculate post-development BNG

During your habitat design process, you must use the metric tool to calculate your post-development BNG value. This will tell you how much BNG you will deliver and if you will meet the 10% objective.

Your calculation must include any:

• on-site gains
• off-site gains – either that you intend to buy or from land you own

You must provide a single metric calculation and BNG boundary plan for your development as part of your outline biodiversity gain plan. This also applies if the project covers multiple LPAs, NCAs, MPAs, and waterbody catchments.

This is also valid for non-contiguous projects with separate areas of development within order limits, and phased developments.

You may have uncertainty about the planned creation or enhancement of some on-site habitat, particularly for later phases of large developments. Wider project uncertainties may also affect a specific area or phase of habitat creation.

If your BNG proposals are not finalised when you submit your outline gain plan, you will need to make assumptions about the enhancements you will likely make.

These assumptions will inform your calculation and the post-development biodiversity value. The value you will submit in the outline gain plan will set the expectations about the biodiversity value of on-site habitats. You will need to include the final value in the updated gain or phase plans.

Find off-site units

You can also deliver your BNG by allocating units from the off-site BNG market.

To explore the off-site market, you could:

• search online – for example, on trading platforms
• consult land agents, brokers or other consultants
• speak with landowners or managers you already have links with
• speak with your LPAs, who may sell or be able to signpost you to sellers in the market
• speak with habitat bank operators

You can consider searching for a gain site that:

• will create and enhance habitat to meet the needs of your specific BNG proposals
• has already started creating and enhancing habitat that meets your BNG needs

You may require large numbers of units and habitat types that are more difficult to create. They may not already be available. You should engage with the off-site market as soon as possible to:

• highlight your upcoming and likely future needs from the off-site market
• allow off-site providers and habitat banks to plan and create the habitats that you need, in the location that you need them
• give land managers a business case to proceed with more demanding habitat creation and reduce their investment risks

You do not have to buy units before you have consent for the project, but you can if you wish. You may wish to explore making flexible arrangements with off-site providers. This can help you demonstrate that you can deliver your BNG objective while allowing for changes as you go through the consenting process.

If you are buying from the off-site BNG market, you should:

• follow your own procurement and due diligence procedures
• seek your own legal advice on the sale with the providers

Estimate costs for statutory biodiversity credits

When you complete your metric calculation, the metric tool will show how many statutory credits you need to buy. The number of statutory credits depends on the number of remaining units you need to meet your 10% BNG.

Before you finalise your designs, you should estimate the total cost of statutory biodiversity credits you need.

Credit prices are set to incentivise developers to use the off-site BNG market. A spatial risk multiplier applies. You will need to buy 2 credits for every one unit you need.

Use or sell excess on-site gains

You can make on-site gains in excess of the mandatory 10% BNG. You may choose to do this, or it could happen because your project creates higher value or more habitats than needed. For example, grassland habitat beneath solar panels may be more valuable for biodiversity than the baseline habitat, and reservoir projects may create excess reservoir habitat units.

With your excess on-site gains, you can do one of the following:

• allocate them to another of your own developments
• sell them to another development on the off-site BNG market
• keep the excess gains for your development
• a combination of these

In all the relevant biodiversity gain plans, you must confirm whether you:

• are keeping the excess gains for your own development
• will make any or all of the excess available to another development

Allocate or sell excess on-site gains to another development

Excess on-site gains that you want to sell or allocate to another development must be treated as off-site gains for the other development.

This is a separate process from your DCO application.

You must meet all other requirements for making and selling off-site gains, including:

• securing with a legal agreement – you may be able to secure your own on-site gains and the units you intend to allocate elsewhere in one legal agreement
• registration on the biodiversity gain sites register
• allocation to the other development

If you wish to sell and allocate, you should follow the guidance for land managers.

Keep excess on-site gains for your development

If you want to keep the excess gains for your development, and for this to be considered as part of your DCO application, these may need to be secured. Refer to the relevant national policy statements (NPS) or discuss with the Planning Inspectorate before submitting your DCO application.

Prepare your DCO application

Your DCO application needs to include:

• an outline biodiversity gain plan
• draft DCO requirements relevant to BNG

Your DCO application will receive consent only if the Secretary of State is satisfied that you are able to meet the 10% BNG objective in line with the relevant gain statement.

Engage early with stakeholders

Engage early with the Planning Inspectorate and other relevant stakeholders. For example, local authorities, planning specialists, and public bodies with statutory responsibilities. This will help to inform your DCO application.

It is important to discuss:

• the BNG objective for your project – as calculated by the metric
• any need for an earlier baseline date to account for habitat degradation
• the drafting of proposed DCO requirements, including if you propose to submit phase gain plans
• the approach to discharging DCO requirements relating to BNG

Plan to secure your gains

You must secure any significant on-site gains, off-site gains or statutory credits for them to count towards your BNG objective. You do not need to secure non-significant on-site habitats for them to count towards your BNG.

Securing your gains means creating a legal mechanism that requires you (or the person you buy the gains from) to:

• undertake the planned habitat creation and enhancement works
• maintain the habitats for at least 30 years
• monitor the works and provide reports to the LPA or responsible body

It is also how you legally assign units to your development.

Secure significant on-site gains

You can secure significant on-site gains with:

• your DCO requirements
• planning obligation (section 106) with an LPA 
• conservation covenant agreement with a responsible body 

You must describe on-site gains in an HMMP. You must include your HMMP:

• within your DCO application – if you are securing any on-site gains through the DCO requirements
• as part of your legal agreement

There is supporting guidance on legal agreements for NSIPs.

The relevant decision maker may also require you to secure non-significant on-site habitats. For example, if locally important habitats are being retained or reinstated. Although they are not considered significant for the purposes of BNG, these habitats may be important for wider planning policy or contribute to locally important species.

Secure off-site gains and statutory credits

You secure off-site gains by registering and allocating them to your development. This applies whether you buy units on the off-site BNG market or if you create off-site units on other land you own.

You secure statutory credits by buying them. They must only be used as a last resort.

When to secure gains

You must include a schedule for securing any outstanding gains in your outline gain plan. This schedule should set out reasonable timeframes for securing gains for agreement with the decision maker.

You do not need to do this if you will have secured all your biodiversity gains by the time you receive development consent, for example, through your DCO requirements, planning obligations or conservation covenants.

You should take into account any uncertainty in your designs and schedule securing your gains throughout the process as you expect your designs to become sufficiently defined.

Once consent is granted, you will need to secure your gains in line with this schedule.

You should secure as many units as reasonably possible before development, or each phase of development, commences.

When you submit your updated or phase gain plans, you may be able to justify that it is reasonable to secure some units soon after development commences instead of before. For example, while you finalise an arrangement that would deliver better ecological outcomes or local benefits instead of buying units that are already registered.

You should only leave a shortfall of unsecured units where there is substantial uncertainty about the exact number or type of units that you need.

You must secure any remaining units before the project, or phase of project, starts operating (carrying out its function) at the latest.

Draft your DCO requirements

You must draft DCO requirements in line with the relevant biodiversity gain statement.

Secure the BNG objective

Your draft requirements must secure the BNG objective. They must secure that you will:

• submit an updated or phase gain plans for approval after you receive consent
• deliver BNG according to the approved outline gain plan and subsequent updated or phase gain plans
• calculate any final shortfall in biodiversity units and secure any outstanding units before the project starts operating

Secure significant on-site gains with DCO requirements

If you are securing significant on-site gains within your DCO application, your draft requirements will secure your on-site gains as described in the HMMP you submit with your DCO.

If the on-site gains that you secured with your draft DCO requirements change, you must update your HMMP and metric calculation, submit them with your updated gain plan and justify the change.

Your draft requirements must secure that you will:

• submit an HMMP for approval with your updated biodiversity gain plan to the discharging authority before commencing the development
• manage and maintain significant on-site gains for at least 30 years from the date the habitat enhancement works are finished
• seek reapproval of an updated HMMP if there are any changes to the significant on-site gains allocated to the development
• submit monitoring reports

Propose your discharging authority for BNG

DCO requirements are typically discharged by a relevant authority before work on much of the development can begin.

For BNG purposes, the discharging authority will have responsibility for approving:

• updated biodiversity gain plans
• any associated documents needed to secure BNG

The discharging authority for BNG may be one of these:

• the host LPA – when your site is within one LPA
• a lead LPA – if the project spans multiple authorities
• the Secretary of State – particularly for complex, multi area projects

The choice should reflect the nature of the project, including:

• the number of authorities involved
• the expected technical complexity of the BNG proposals
• the capacity of the relevant authorities to carry out the role

Before submitting your DCO application, you should discuss with the Planning Inspectorate and the relevant LPAs:

• your intended discharging authority
• the need for any consultation or coordination arrangements – especially if the Secretary of State or the lead LPA will act as the discharging authority
• expected timings and the appeals process for discharging DCO requirements related to BNG

These early discussions will help all parties to agree the approach. They will also reduce the risk of delays during examination or after consent.

You must name the chosen discharging authority in your DCO application, along with any other host or relevant LPAs to consult with.

Appeals mechanism for updated or phase gain plan refusal

You can include an appeals mechanism in your DCO application, as outlined in the planning guidance.

You should consider whether your proposed appeals mechanism will:

• be suitable if the LPA refuses or fails to approve an updated biodiversity gain plan, HMMP, or other relevant BNG information
• include an option for appeal if the LPA fails to make a decision in a specified timeframe

Create an outline gain plan

Your outline gain plan must include the details set out in the relevant gain statement.

This includes:

• a strategy for meeting the BNG objective, whether on-site, off-site or through statutory credits
• a schedule of timings for when you propose to allocate off-site gains to the development after consent
• a description of any remaining uncertainty and how any changes to your BNG objective will be addressed

You will need to update your outline gain plan for approval from the discharging authority before you can start the development works. This approach gives flexibility for projects with evolving designs. It also makes sure BNG is secured at appropriate stages.

You will need to provide details and justification for any material changes between the approved outline gain plan and the updated or phase gain plans. The level of scrutiny for any changes should be proportionate to the significance of the change.

Outline gain plan for phased developments

If you are delivering your development in phases, you can submit biodiversity gain plans for approval on a phased approach.

You might wish to do this if the detailed designs of all phases are not known when you submit your DCO application.

Your outline gain plan must include:

• BNG proposals for the whole development site – this is because the examining authority will need to review if your overall plans will meet the 10% BNG objective
• confirmation that you will submit detailed phase gain plans after consent
• information about how each phase is expected to contribute towards the BNG objective

You may not have finalised the details of your proposals for some phases of the development. In this case, you should provide information on certainty levels for each phase and the assumptions you have made in your outline gain plan.

You must achieve 10% BNG for the entire development. The contribution of each phase towards the overall 10% will vary. If a later phase of the development does not go ahead, or is not completed, you must make sure that 10% BNG is still achieved for the development you have done. You may need to update your metric calculation and updated gain plans and secure any shortfall in units.

Provide evidence of what’s in your baseline

Your outline gain plan must include a BNG boundary plan. This must clearly show, and differentiate between:

• negatively impacted habitat
• areas of habitat that will be used to contribute towards BNG for your development
• unimpacted habitats included in baseline
• unimpacted habitats excluded from the baseline

Your BNG boundary plan must:

• show the entire order limits, with the BNG boundary overlaid
• be drawn to an identified scale
• show the direction of north
• have a clear legend showing the different categories of habitat listed above

If your baseline excludes areas of unimpacted habitat within the order limits, you should explain why or how the habitats will remain unimpacted in your outline biodiversity gain plan. You should also set out the assumptions or parameters you used.

For example, you could describe any measures you will use to prevent negative impact or provide evidence that construction will avoid the habitat area. This can include cross-referencing other application documents to avoid duplicating information, such as construction or works plans.

What to include in your outline gain plan when you have design uncertainty

If you have areas of design uncertainty when you submit your outline gain plan, you should clearly explain and justify:

• your assumptions and design or construction parameters used to identify impacted habitats in your baseline
• why they represent the most realistic worst-case approach

Where relevant, you should also describe:

• any mitigation or avoidance measures you will use to prevent impacts
• alternative habitat impacts that could arise under other realistic design or construction options
• how you would secure additional biodiversity units if those alternative impacts occur

The level of detail should be proportionate to the value of the habitats, ease of habitat creation and availability of units in the off-site BNG market. If you do not end up impacting these higher-value habitats, you can update your calculation in your updated or phase gain plan to account for this.

Describe your off-site strategy

If you deliver any BNG off-site, you should demonstrate in your outline gain plan that you will be able to allocate the necessary units to your development after consent. You should include any:

• evidence of unit availability
• arrangements with habitat providers to reserve or secure units
• agreements with habitat providers to create units you need

The evidence you choose to include should vary depending on your unit needs, the availability in the off-site market and how easy it is to create units for that habitat type.

If your outline gain plan does not provide sufficient assurance that you can buy the units you need, you are likely to face more scrutiny during the consenting process and risk delays.

Provide evidence of the need for statutory credits

If you think you will need to use statutory credits, you must include it in your outline gain plan.

You will also need to include justification that you intend to use them as a last resort because you cannot deliver all your BNG through on-site and off-site gains.

This evidence should show that you followed the relevant gain statement and the supporting guidance to:

• consider BNG early in project development
• engage early with the off-site BNG market

After you receive your development consent

Once your DCO application is approved, you will need to:

• secure your units in line with the schedule in your outline gain plan – unless already secured with your DCO requirements
• provide an updated or phase gain plans for approval to the discharging authority

Allocate off-site gains to your development

Once you have development consent, you can allocate units to your development, including those you may have bought earlier.

After consent, you may also need to buy and allocate more units if your metric calculation has changed or if you did not buy enough to meet your BNG objective before consent.

The land manager, or you with their permission, must allocate the off-site units to your development. This is done on the biodiversity gain sites register.

If the biodiversity gain site you have chosen is not yet registered, you can either apply to:

• record the allocation of gains to your development after the seller has registered the gain site
• record the allocation of gains to your development at the same time as applying to register the site

Before development can commence, you will need to have secured as many units as reasonably possible in line with the schedule agreed in your outline gain plan.

Buy statutory credits

If you are unable to deliver BNG through on-site and off-site options, you will need to buy statutory credits as a last resort.

Before you submit your updated or phase gain plans, you should begin the process of buying any statutory credits that you need. You will need to have finalised the purchase before you can commence development.

If you still have substantial uncertainty about the exact number or type of credits you need when you submit your updated or phase gain plans, you can buy any further statutory credits during or after construction. You must buy all required credits before the operation of the project starts.

Material or non-material changes to your DCO

The mandatory 10% BNG objective does not apply specifically to change applications. However, the Secretary of State may consider any changes in your biodiversity value as a relevant and important matter when deciding the change application.

In your change application, you should provide information about whether and how the proposed change affects your development’s BNG objective. Where it does, you should set out how you will amend your BNG strategy so that you can continue to meet the objective.

Create your updated or phase gain plans

Your outline biodiversity gain plan will have provided preliminary evidence and information on your BNG proposals.

Before commencing your development, or each phase, you must submit an updated or phase biodiversity gain plan for approval from the discharging authority.

This plan will set out your final approach to delivering BNG, or BNG for the next phase, now that there is more certainty for the project or phase. It must:

• implement the biodiversity objective as set out in the approved outline biodiversity gain plan
• account for any updates to your development plans since you submitted your outline gain plan
• amend the baseline date to the date you submit your updated gain plan to reflect the current site conditions

Your updated or phase gain plan must include all items listed in the relevant biodiversity gain statement. This includes:

• an updated metric calculation – using an updated baseline date where needed
• details and justification for any changes to on-site habitats, habitat impacts or development plans compared to the approved outline gain plan
• an updated HMMP – if there have been changes to planned on-site habitats secured through requirements in the DCO
• supporting evidence for any changes – such as updated construction or works plans, engineering drawings, or details of impact prevention measures
• an updated BNG boundary plan if there have been any changes, or confirmation that the original BNG boundary still applies
• evidence of any biodiversity units that have already been secured (on-site or off-site) – including the biodiversity gain site register reference number
• evidence of any statutory credits that have already been purchased
• a strategy to secure any remaining biodiversity units or buy statutory credits and planned times

You should use version control to clearly label any updates to BNG boundary plans, metric calculation tools, and the supporting justification.

For phased developments, you must describe in detail what BNG proposals you:

• have already done
• plan to carry out as part of the current phase
• will need to deliver over the remaining phases – you may still have uncertainty for later phases of the development

When to update your metric calculation

You must update your metric calculation, including your baseline where needed, if there will be a greater impact on biodiversity than you predicted in your outline gain plan. This could be because:

• your updated development plans change the BNG boundary and result in a greater impact on habitats
• changes you have made to your planned on-site BNG delivery result in greater impacts to habitats or lower provision of on-site BNG
• the value of existing on-site habitats being impacted has naturally increased with time

You may choose to update your calculation if, compared to the outline gain plan:

• there are reduced impacts to habitats
• the condition of any on-site habitats has naturally reduced
• you will deliver more on-site gains than previously planned

Your updated or phase gain plan will need to include evidence of what has caused changes to the impact on habitats.

Baseline date for updated plans

For updated and phase gain plans, your baseline must reflect the site conditions on the date you submit your updated gain plan unless you used an earlier date in the outline gain plan.

Where you used an earlier date, the baseline date you use for your updated or phase gain plans will depend on the current habitat value compared to what you used in the outline gain plan. You should:

• continue to use the earlier date for all current habitats of lower value
• use the date you submit your updated or phase gain plan for all current habitats of higher value

The gain statements also cover special provisions for any degradation of habitat between submitting the DCO and any updated or phase gain plans. This includes activities permitted through your DCO that result in loss or negative impact to biodiversity.

In case of degradation, you should use an earlier baseline date. You should use one of the following:

• the date immediately before the degradation activities were carried out
• the closest date before degradation for which you have accurate data

If there is insufficient evidence about the biodiversity value of the on-site habitat immediately before the degradation, you can use the baseline date from your outline gain plan.

You should:

• agree the earlier date with the discharging authority
• include justification and evidence for the earlier date in your updated gain plan

When to resurvey for updated plans

The gain statements set out the requirements around survey validity for the updated or phase gain plans. They state that you can use the same survey data from the outline gain plan if your ecologists confirm that there have been no material changes to the habitats.

You will need to resurvey the relevant part, or all of the site, if:

• there have been any material changes to habitat conditions
• you had gaps in your survey for your outline gain plan, for example due to access constraints

Your ecologist should help you understand if you need to resurvey your site. You should inform them if you know of any changes to the land use or management of the site.

Appeal an updated or phase gain plan refusal

If you included an appeals mechanism in your DCO application, you can use this to appeal a decision of a discharging authority.

Before you can commence development

The development, or phase of development, cannot legally commence until all pre-commencement requirements in the DCO have been discharged.

Before the project starts operating

You must have finalised and secured the delivery of your BNG before you commence operation of the project. This means you must:

• update the metric calculation if any additional impacts occurred during construction that have not already been accounted for – for example, where planned horizontal directional drilling was not possible
• cover any shortfall in your BNG delivery – likely through the off-site BNG market or from statutory credits as a last resort
• provide evidence that you have met your BNG objective to the discharging authority for their approval

For a phased project, you can commence operation when you have finalised and secured the BNG objective for that phase. You cannot commence operation of the final phase that you intend to build until you have finalised and secured the BNG requirement for the whole project.

You should still take these steps even if the development never operates.

Manage, monitor and report on gains

Significant on-site gains or off-site gains on other land you own

You are responsible for making sure the habitat is managed and monitored for at least 30 years. This starts when the habitat creation and enhancement works are complete, as defined in your legal agreement.

Your HMMP will set out what management, monitoring and reporting you must do. You are responsible for making sure that:

• the management actions in your HMMP are delivered
• monitoring surveys are carried out
• monitoring reports are sent to the discharging authority

If you do not uphold your responsibilities from your HMMP, you might be in breach of your DCO or legal agreement. The discharging authority could take enforcement action against you.

If your development is going to operate longer than 30 years, you should continue to maintain the habitat for at least the whole period of operation.

If you buy off-site units

It is the landowner’s legal responsibility to make sure that the actions from the HMMP are undertaken. This includes managing, monitoring and reporting throughout the 30-year management period.

Case studies on the statutory biodiversity metric

Natural England provides case studies demonstrating the use of the statutory biodiversity metric. These are not specific to NSIPs, but examples on port development, river restoration and offshore wind cabling may be relevant.

Further information

The Ministry of Housing, Communities and Local Government (MHCLG) provides NSIPs guidance on:

• national infrastructure planning
• what to include in your draft DCO

British Standards 8683 - Process for designing and implementing BNG, from the British Standards Institution. There is a cost to buy this for non-BSI members.

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