HMRC must send a formal notice if it intends to start an enquiry into a self-assessment tax return. It has a limited time to do this. Before responding to any questions asked by HMRC check that the enquiry notice has been issued in time. If not advise HMRC that it is out of time.
Deadlines
HMRC can begin an enquiry into a self-assessment personal or company tax return by issuing a notice in writing that is received by the person or company within the so-called enquiry window. If it is invalid the enquiry cannot proceed.
The enquiry window deadlines are:
Personal tax returns
Amended personal returns
You are allowed to amend a tax return up to twelve months from its filing date, whether that’s the normal filing date or later because HMRC requested the return late. A different enquiry window to applies to the amendment.
For example, if 2022/23 HMRC issued a notice to file after 31 October 2023 the normal filing date of 31 January 2024 would not apply. Instead the filing date would be three months from the date the notice to file was issued (not when it was received). For example, if this date is 1 November 2023 the filing date for the purposes of amending the return is 1 February 2024. A taxpayer can make an amendment to their return up to 1 February 2025.
The amendment does not change the enquiry period for the return, which is explained above.
There is however a separate enquiry window for the amendment. The enquiry period for the amendment is up to the quarter day next, following the first anniversary of the date that the amendment was made.
The quarter days are 31 January, 30 April, 31 July and 31 October.
Company tax returns
If the notice arrives after the enquiry window has ended use our Enquiry - Notice Out of Time Letter to inform HMRC.
Note. If HMRC received the return after 31 January, it has “up to and including the quarter day next following the first anniversary of the day on which the return was delivered…” (s.9A(s)(b) of the Taxes Management Act 1970) within which to issue the notice of enquiry.