Taxes Management Act 1970 Schedule 1A paragraph 3

Amendments of claims

Schedule 1A paragraph 3 sets out the time limits within which a tax claim may be amended, either by an HMRC officer or by the claimant, and the circumstances in which amendments are temporarily prohibited.

• An HMRC officer may amend a claim within nine months of the date it was made, to correct any obvious errors or mistakes, whether errors of principle, arithmetical mistakes or otherwise.
• The claimant may amend their own claim within twelve months of the date it was made, by giving notice to an HMRC officer.
• No amendment may be made by either party once HMRC has opened an enquiry into the claim, until that enquiry is completed.
• The restriction on amendments runs from the day the officer gives notice of intention to enquire until the day the enquiry is formally completed.