HMRC Aware of Bug Affecting Online RDEC Submissions

On the 8th of August 2023, HMRC introduced the additional information form (AIF) which must be completed and submitted for all R&D tax relief and expenditure credit claims going forwards. HMRC is aware of a glitch whereby taxpayers or agents are unable to complete the 655 and 657 boxes on the CT600, resulting in an ‘Error 9283’ message for RDEC applicants.

Error 9283 — Box 655 can only be completed if at least one of the boxes 670 or 680 is greater than 0 (zero).

HMRC has advised RDEC claimants to not make entries in boxes 655 and 657 until it updates the service in April 2024 with a fix. Businesses seeking to claim against the R&D Tax Relief (SME) scheme are seemingly unaffected by the error. Boxes 655 and 657 on the CT600 relate to:

  • 655 – Put an ‘X’ in box 655 if the claim is made by a large company.
  • 657 – Put an ‘X’ in box 657 to confirm that an additional information form has been submitted.

Despite the bug, claimants still need to submit an AIF prior to the submission of their CT600 to make a valid R&D Expenditure Credit (RDEC) or R&D Tax Relief (SME) claim.

How Cost Care Tax can help

Now more than ever, we recommend consulting an R&D tax specialist to ensure your claims comply with HMRC’s new stringent criteria and are as robust as possible. If you have any questions regarding how the new HMRC regulations might impact your R&D tax relief/credit claims or want to talk directly with a tax professional about how Cost Care Tax can help you, please contact us on 0161 904 0044 or

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We have referred tens of clients to Cost Care Tax over the past 7/8 years and all have been impressed with the professionalism and efficiency of their team. The support in relation to R&D tax claims is unrivalled and exceptional and we highly recommend them. Thanks to Wayne, Paul, Tom, Ben and the rest of the team
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