Changes and issues affecting the Corporation Tax online service

Check the following Corporation Tax online service issues.

Non-ResidentFirst-year Company allowance for zero-emission cars

InAs Aprilannounced 2023,at theAutumn mainBudget Corporation2024, Taxthe rate100% wasfirst-year increasedallowance from 19% to 25%. A small profits rate (SPR) of 19% for profitsqualifying belowexpenditure £50,000on andzero-emission marginalcars reliefhas (MR)been wasextended introduced for profits between £50,000 and £250,000.  

Non-resident companies, without a permanent establishment within the UK, are either not:

• eligible to use31 theMarch SPR
• entitled2026 tofor MR

YouCorporation mustTax usepurposes. theFind mainout taxmore rateabout whencapital calculating the tax on any profits.allowances.

We are aware ofthat a small percentagenumber of non-residentcompanies customerswith thatan haveaccounting filedperiod returnsstarting toon HMRCor usingafter an1 incorrectApril tax2025 rateand orthat haveintend appliedto MR.   

Tosubmit avoidtheir thistax error,return usebefore companyApril type2026, 2may (labelledbe asunable Closeto investment-holdingreport company)their inclaim Boxfor 4this toallowance ensurein onlyboxes the726 correctand rate751 of taxthe is applied. CT600.

TheIn April 2026, the Corporation Tax online service will be updated in April 2025 to includesupport athe newextended companyperiod type for non-residentclaiming companies, which will remove this issue.  

Iffirst-year aallowance. companyBefore hasApril already2026, filed,if andyou wedo identifyneed theto error,submit wea willclaim correctfor itsan return.accounting Aperiod:

• beginning Noticebefore of1 CorrectionApril (CT620)2025, willyou becan issuedcontinue advising the additional liability to pay.   

  Ifdo aso Noticeusing ofboxes Correction726 (CT620)and is751

• beginning receivedon butor theafter company1 believesApril it2025, isreport eligibleyour toclaim usein theboxes SPR725 orand apply750 MR,(other theyallowances canand email csg.nr.correction.query@hmrc.gov.uk for HMRC to investigate their individual case.
  charges)

Research and Development expenditure credit (RDEC) claims

HMRC introduced the additional information form on 8 August 2023. You must submit this for all claims for Research and Development (R&D) tax relief or expenditure credit.

SmallResearch and medium-sizedDevelopment enterpriseexpenditure credit (SMERDEC) subcontractorclaims towhich aare largeexempt companyfrom the PAYE cap

WeThe aremerged awarescheme thatR&D customersexpenditure whocredit are only claiming (RDEC) asand aenhanced SMER&D subcontractorintensive tosupport a(ERIS) largereplaced company,the areold unableRDEC toand completesmall bothand boxesmedium-sized 650enterprise and(SME) 657schemes for accounting periods beginning on formor CT600.after Completing1 theseApril boxes2024.

We signifiesare aware that athere SMEis subcontractorno hasoption submittedon the additionalCT600L informationfor form.

Ifcustomers you’reto affectedindicate bythat thisthey issue,are youclaiming mayexemption getfrom the followingPAYE error:

If you are affected,claiming doan notexemption, you should make entriessure that the amount entered in boxesbox 650L75 andequals 657.the amount entered in box L70. This is so that the amount of step 3 restriction carried forward to the next accounting period in box L80 is ‘0’.

You must still submitalso theadd additionala informationnote formin toyour makecomputations, or in a validPDF RDECattachment claim.with your Corporation Tax return, that you are claiming an exemption under section 1112E CTA 2009.

We will update the service in April 20252026 to fix this issue.

Creative industries

HMRC introduced the additional information form on 1 April 2024. You must submit this for all claims for creative industry tax reliefs or creative industry expenditure credits alongside the Company Tax Return. Use this new mandatory form to share supporting evidence, either before or on the same day the Company Tax Return is submitted.

HMRC planned to introduce new supplementary form CT600P for all creative industry claims for returns submitted from April 2025.

Due to a restriction within the updated HMRC Corporation Tax online service, we are aware that customers claiming one or more of the creative reliefs and credits will be unable to include the CT600P with their return.

We have therefore decided to temporarily postpone the requirement to include the CT600P in your return until April 2026. In the meantime, you should use this guidance.

Cultural Reliefs and Film, High End TV, Children’s TV, Animation and Video Games tax relief

Complete box 540 with the gross amount of your credit claim and box 885 with any balance of payable tax credit.

Audio-Visual Expenditure Credit (AVEC) and Video Games Expenditure Credit (VGEC)

If your software supports the new AVEC and VGEC boxes 541 and 886, complete box 541 with the gross amount of AVEC or VGEC and box 886 with the balance payable.

If your software does not support the new boxes, complete box 540 with the gross amount of AVEC or VGEC and box 885 with the balance payable.

Read more about the new creative industry expenditure credits.