There are strict time limits relating to tax returns for HMRC as well as taxpayers. How long does HMRC have to start an enquiry into your personal self-assessment return?

Tax enquiries

None of us is likely to thank HMRC for starting an enquiry into our tax return. The best way to view one is as a necessary check that only collects tax from those who avoid it unfairly so that you and other law abiding taxpayers don’t have to pay more. However, tax inspectors are known to sometimes overstep their authority and so you need to be on your toes.

Enquiry window

HMRC is bound by a rigid timetable in which it can open an enquiry into your or your business’s tax returns. This is known as the “enquiry window”, and it can be a little tricky to get to grips with. If your return is submitted to HMRC:

  • on or before the normal deadline, it has up to twelve months from the date your return was submitted to start an enquiry
  • after the normal deadline, the enquiry window runs until the next quarter day (30 April, 31 July and so on) following the first anniversary of when you submitted your return. For example, if you submitted your 2019/20 return on 1 April 2021 (two months and a day late), the enquiry window ends on 30 April 2022.

What if I amend my return?

You can amend your tax return at any time within the twelve months following the deadline for submitting it. The amendment doesn’t change the enquiry window for the original return, instead there’s a separate enquiry window for the amendment. It runs from the date you made the amendment to the quarter day that follows its first anniversary.

Tip. Where an enquiry is started after the window for the original tax return, but within that for an amendment, HMRC can only make enquiries regarding the amendment. This is a point sometimes overlooked or not understood by tax inspectors.

Earlier year information?

Another mistake made by overly keen inspectors is to ask for information about periods prior to that covered by the tax return they are investigating. They shouldn’t do this. If they do you should politely but firmly refuse to provide it.

Out of bounds

Tax inspectors have been known to argue that they can’t properly check the figures for the year they are enquiring about without understanding how a figure for an earlier year was arrived at. Typically this happens where they are reviewing figures in accounts which include adjustments brought forward from an earlier year. For example, the opening value of equipment which qualifies for capital allowances. This is a spurious argument and again you should politely refuse the request.

Discovery. If an inspector wants to question a figure outside the enquiry window, they must raise a special assessment, known as a discovery assessment. However, these too are governed by rules which prevent them taking liberties.

This article has been reproduced by kind permission of Indicator – FL Memo Ltd. For details of their tax-saving products please visit www.indicator-flm.co.uk or call 01233 653500.