Self assessment ― amendments and corrections

Produced by Tolley

The following Personal Tax guidance note Produced by Tolley provides comprehensive and up to date tax information covering:

  • Self assessment ― amendments and corrections
  • Correction
  • Amendment
  • Amending a tax return
  • Call for evidence
  • What if the taxpayer misses the deadline to amend the return?
  • Recovery of overpaid tax
  • What claims for overpaid tax will be accepted?
  • Disclosure of underpaid tax

Self assessment ― amendments and corrections

Once a self assessment tax return has been filed, both HMRC and the taxpayer (or the agent) has the right to make changes to the return. There are different time limits depending onwhether it is a correction by HMRC or an amendment made by the taxpayer.


HMRC has the right to amend the tax return within nine months of the date of receipt (ie the date the return was filed rather than the due date for filing) without opening an enquiry. Usually, HMRC does this to eliminate or to reverse any obvious errors or mistakes within the return. These are usually arithmetical errors, although HMRC can reverse any technical mistakes made by the taxpayer in completing the return.

HMRC will notify the taxpayer of any amendments made. The agent should receive a copy of this notification. The taxpayer is not bound to accept the correction. The correction can be rejected within 30 days of the date the notice was issued by HMRC (ie not the date of receipt of the notice). If you need to reject the correction, it is suggested that you do so in writing, stating the reason(s) you believe the correction is incorrect.

If the correction is rejected and HMRC does not agree with the reason for the rejection, it is likely that the Officer will open an enquiry into the return. See the Types of checks onreturns guidance note.

For further reading, see Simon’s Taxes E1.214.


The taxpayer also has the right to amend the return already submitted, so long as this is within 12 months of 31 January following the end of the tax year (eg 31 January 2023 for a 2020/21 tax return). This is the deadline irrespective of whether the return was filed onpaper or electronically.

The only exception to this is where the tax return is not issued until after 31 October following the end of the tax year. This can

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