Errors/mistakes on previous Returns.

Many individuals try to complete their Self-Assessment Tax Returns without seeking professional help. In some cases, they claim more than they are entitled to which can lead to a Revenue enquiry. Alternatively, allowable expenses are sometimes missed and allowances may go unclaimed. The self-employed sometimes miss claims for “use of home”, business use of mobile phone, and the mileage rate for business use of vehicles. The tax system for the retired can be complicated and claims for the “Married Couples Allowances” are not made.

If expenses or allowances have been missed then Overpayment Relief can be claimed where the taxpayer has made a mistake on their Tax Return which has led to more tax being assessed than should be, or when HMRC has made a determination of tax due and the taxpayer believes it to be incorrect. We can usually go back 4 years so for a discovery in the year ending 5 April 2019 claims from 2014/15 can be lodged.

How to make a claim.

The claim must be made in writing and should say:

  • you are claiming Overpayment Relief,
  • how much you think you have overpaid,
  • the years or accounting periods involved,
  • why you think Overpayment Relief is due,
  • whether an appeal in respect of this has previously been made.

Send the letter off to your Tax Office with documentary proof of the tax deducted (if appropriate) and a signed declaration stating that the information given in the claim is complete and correct to the best of your knowledge and belief.


HMRC notes on this can be found here.

Published 4 October 2017.

Updated 6 April 2018.