HMRC issue with CT600

HMRC acknowledges validation errors in filing form CT600 with RDEC claims

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As you will know, businesses with an accounting period starting on or after 1 April 2021 must now complete the new boxes on the CT600L when claiming Research and Development Expenditure Credit (RDEC) and/or R&D payable tax credit for SMEs.

However, HMRC validation is rejecting returns being filed from April 2022 where the period started before 1 April 2021. This impacts where businesses are only claiming SME Research and Development Enhanced Expenditure (included in box 660) but no other R&D tax relief, so would not be completing a CT600L – for example, a year-end of September 2021 (period start August 2020, ie pre-1 April 2021) and being filed in April 2022.

The HMRC validation is rejecting returns being filed from April 2022 with a box 600 inclusion but, correctly, nothing being completed for CT600L.

HMRC has said it is in the process of adding it to the CT service issues page. Affected customers will have to either:

  • wait until the CT service is updated to file, or
  • submit their return on paper.

Thank you to our members who highlighted this issue. Please do continue to feed through your insights to advisory@accaglobal.com.

Further resources

HMRC CT600 completion guide

ACCA research and development checklist