If, after you have filed your tax return, you become aware that an entry is incorrect, you can amend that return if you are in time to do so. Also, if you have used provisional figures when you completed a tax return, you will need to amend your tax return when the actual information becomes available.
If you realise you have made a mistake on your tax return, you should amend it as soon as possible to correct the error.
If you used provisional figures when you originally completed your tax return because you were missing some information, you should amend the tax return to replace the provisional figure with the actual figure as soon as the relevant information becomes available.
We explain below what the deadline is for amending a return and what to do if you miss the deadline.
You can amend your return any number of times before the amendment deadline.
You have up to 12 months from 31 January following the end of the tax year to which the tax return relates to make the amendments. If the notice to file the return was issued after 31 October, you can amend the tax return within 15 months of that notice being issued.
Therefore, if you need to amend your 2022/23 tax return you normally have until 31 January 2025 to make the amendment. This applies regardless of whether you filed a paper return or you filed online. If, for example, you did not receive a notice requiring you to file your tax return for 2022/23 until 12 December 2023, then you can amend it up until 11 March 2025.
If you need to amend your tax return outside of the above time limits, HMRC say you should write to them to explain what has happened. The information you need to include in your letter is set out on GOV.UK. You may wish to get help depending on the circumstances.
If additional tax is due as a result of the amendment, HMRC will let you know what you need to do to bring your tax affairs up to date. This may involve making a formal voluntary disclosure to HMRC.
If tax has been overpaid, you may be able to make a claim for overpayment relief to obtain a refund. You can read about how to do this on our page Self assessment tax refunds.
If you filed your original tax return online, you can make the amendment online through HMRC’s self assessment portal. You can also make the amendment on paper by writing to HMRC.
If you used third party software to file the return originally, you should use this to make the amendment.
Paper filers should make any amendments on paper. For more information, see GOV.UK.
If you claimed the fourth and/or fifth self-employment income support scheme (SEISS) grants during the coronavirus pandemic, you will need to consider whether changes to your tax return(s) for 2016/17 to 2019/20 mean you were not actually eligible to claim these grants, or whether the grant(s) received should have been less.
