Simple assessment – take care to ensure you don’t overpay tax

What is simple assessment?

Simple assessment is a process used by HMRC to collect tax from people who don’t have to file a self assessment tax return and who have income which is not taxed through pay as you earn (PAYE), such as interest on savings or state pension income.  You can find out more information about the process on our dedicated simple assessment guidance page.

HMRC usually issue simple assessments in the summer months, following the end of the tax year. These calculations are based on the information HMRC have on their records at that time. Most people only receive one simple assessment calculation. HMRC sometimes receive information about taxable income later, meaning a replacement simple assessment calculation needs to be issued.

What is happening now?

We understand that HMRC have recently started to issue a further wave of simple assessment tax calculations for the tax year ended 5 April 2025. These calculations include interest income based on information shared with HMRC by banks and building societies.

For some people, this might be the first simple assessment they have received for tax year 2024/25. For others it might be a replacement calculation, following a previous simple assessment earlier in the year.

What to look out for

If you receive more than one simple assessment calculation for tax year 2024/25 then it is important to remember that the most recent calculation will replace the previous version received.

  If you have already made a payment in respect of an earlier calculation for tax year 2024/25, it is important to note that those tax payments are not shown on the updated version of the calculation now being issued.  Therefore, the new version of the calculation might indicate that you owe tax which, in fact, you have already paid.

Understandably, this is causing some confusion amongst taxpayers. 

Checking your simple assessment

To check a simple assessment calculation for tax year 2024/2025:

1. Carefully review the calculation and make sure that you agree with the amounts shown, as noted in our simple assessment guidance. Interest and dividends from ISA accounts and amounts which are within your personal savings allowance and dividend allowance should not be included in the calculation, as no tax is due on this income.
    
2. Consider whether you are entitled to claim any tax reliefs which aren’t already included on your tax calculation.  For example, this could be tax relief due on charitable donations made under a Gift Aid declaration or on some types of pension contributions. Claiming these tax reliefs might decrease your tax liability if you are a higher rate taxpayer.
    
3. If any changes are needed to the calculation or you need to query any of the figures, contact HMRC within 60 days of the date of the simple assessment letter. Details of how to contact HMRC can be found on GOV.UK. HMRC will be able to give you more information about the amounts included in your calculation and will issue an updated calculation if they agree this is necessary.
    
4. Check the amount you need to pay. If this simple assessment is replacing an earlier calculation for the same tax year, the total amount showing as due will not reflect any payments you may have already made. You can check what you have already paid through your personal tax account, which you can access via GOV.UK, or by calling HMRC. HMRC say that you only need to pay the remaining balance.
    
5. When you have confirmed the amount of any tax that you still owe for tax year 2024/25, after taking into account any payments you have already made, ensure that you pay the balance of your simple assessment liability by the relevant due date, as follows:

• If the date shown on the 2024/25 simple assessment is 31 October 2025 or earlier, the payment due date is 31 January 2026.
• If the date shown on the 2024/25 simple assessment is 1 November 2025 or later, the payment due date is 3 months after the date of the assessment.

Payment instructions can be found on GOV.UK, along with information on setting up a payment plan if you can’t make the payment by the due date.

If you file a self assessment tax return and also receive a simple assessment calculation, you can contact HMRC and ask them to withdraw the simple assessment.

What if I overpay?

If you think you have paid more tax that you owe you should contact HMRC using one of the methods detailed on HMRC’s website GOV.UK to discuss your position and request a refund if one is due.

Summary

If you receive a simple assessment calculation from HMRC check it carefully.  This is particularly important if you receive an updated version of the calculation from October 2025 and you have previously made a simple assessment tax payment for tax year 2024/25, as you might not owe the full amount of tax shown on the latest calculation.