Understanding simple assessments

Written by AJN Accountants
4 December 2025

If you owe income tax that cannot be collected automatically via PAYE, such as tax on bank interest or the state pension, HMRC may send you a simple assessment notice.

This letter shows how much tax HMRC believe you owe based on information they hold. It is important to check the figures against your own records, including bank statements and letters from the Department for Work and Pensions.

If you normally complete a self assessment tax return you should not also receive a simple assessment. If you do, HMRC must withdraw it. You have 60 days from the date on the notice to challenge the figures or request withdrawal. We can help you with this.

Most people will receive only one notice, but it is possible to get more than one for the same tax year. For example a taxpayer who has already received a letter for 2024-25 that did not include their bank and building society interest may receive a second letter taking that information into account. The updated notice will show the total tax due for the year, even if some has already been paid. Make sure you deduct any tax paid following the first letter from the tax shown as due in the second letter before paying the remaining balance.

The payment deadline depends on when the notice is issued. If it is dated before 31 October, the tax must be paid by 31 January the following year. For notices dated on or after 31 October, you have three months from the date of issue to pay the tax. If you cannot pay in full, HMRC’s new self-serve Time to Pay system allows you to set up an instalment plan online.

Simple assessment letters are now being issued for income earned in the 2024-25 tax year. Contact us if you have received a letter and you are not sure whether the calculation is correct.

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