A Simple Assessment is a tax bill that HMRC works out for you, without a tax return, when you owe Income Tax it cannot collect through your tax code. The letter is known as a PA302. For the 2025/26 tax year, a letter issued on or before 31 October 2026 must be paid by 31 January 2027. A letter issued later is due 3 months after the date it was issued. If you think the figures are wrong, you have 60 days from the date of the letter to query them. HMRC expects to send around 1.8 million of them for 2025/26.
Why you have received a Simple Assessment
After each tax year ends on 5 April, HMRC checks the tax you paid against information from employers, pension providers, the Department for Work and Pensions and banks and building societies. If you paid too little and the shortfall cannot be added to your tax code, it sends a Simple Assessment instead. HMRC's guidance gives these as the usual reasons:
- State Pension above the personal allowance. The State Pension is taxable but paid without tax deducted, so if it takes your income over the £12,570 personal allowance there may be tax to collect;
- Untaxed savings interest or dividends. Banks report the interest they paid to HMRC after the year ends, and tax is due on interest above your allowances;
- A second income that was not taxed. For example, a small pension or job where the wrong code was used;
- Too much tax-free allowance. You were given more allowance through PAYE than you were entitled to;
- Larger debts. HMRC will normally collect an underpayment through your code only if you owe less than £3,000. Larger amounts are usually billed by Simple Assessment.
You will not receive one if you are in Self Assessment. Section 28H of the Taxes Management Act 1970 allows HMRC to make a Simple Assessment only if you have not filed a tax return for the year and have not been sent a notice to file one. Any underpayment is dealt with through your return instead.
A worked example
HMRC's own example shows how pensioners end up with a bill. Someone receives a State Pension of £16,000 a year, including Additional State Pension, and a private pension of £1,500. Their income of £17,500 is £4,930 above the £12,570 personal allowance, so they owe 20% of £4,930, which is £986.
The only place tax can be deducted during the year is the private pension, and HMRC can collect no more than 50% of that pension through a tax code, which is £750. The remaining £236 is collected by a Simple Assessment after the year ends.
When you have to pay
The due date is set by section 59BA of the Taxes Management Act 1970 and depends on when HMRC issued the letter:
| Letter for 2025/26 issued | Payment due |
|---|---|
| On or before 31 October 2026 | 31 January 2027 |
| After 31 October 2026 | 3 months after the date of issue |
For example, a letter dated 14 August 2026 must be paid by 31 January 2027, while a letter dated 20 November 2026 is due on 20 February 2027. HMRC sends letters in waves. Working-age customers began receiving 2025/26 letters from 30 June 2026 and pensioners from 12 August 2026. A second batch, based on bank and building society interest data, goes out between October and December 2026, so many of those letters will have a 3-month deadline rather than 31 January.
You can pay in full or in smaller amounts, as long as the whole amount is paid by the deadline. You need the 14-character payment reference starting with X shown on the letter. You can pay through the HMRC app, online, by bank transfer or by cheque. If you use the wrong reference, the money may be put against a different tax bill.
Checking the calculation
A Simple Assessment is based only on the information HMRC holds, and that information is sometimes wrong. Check the letter against your own records before paying:
- Pay and pension figures. Compare them with your P60, P45 or pension statements;
- Interest. Compare with your bank statements. Interest on a joint account is split equally between the holders unless you tell HMRC otherwise;
- State benefits. If you are paid every 4 weeks, multiply the payment by 13, not 12, to get the annual figure;
- Adjustments. Items such as Marriage Allowance or tax owed from an earlier year are often included in the adjustments total rather than shown separately.
HMRC may issue more than one Simple Assessment for the same year if new information arrives. The latest letter shows the total tax due for the year. If you have already paid an earlier bill, you only pay the difference. For example, if you paid £300 and a later letter shows £450, you owe a further £150.
If you think the figures are wrong
Section 31AA of the Taxes Management Act 1970 gives you the right to query a Simple Assessment within 60 days of the date it was issued, or longer if HMRC allows. Call or write to HMRC and explain which amounts you think are wrong, what they should be and which records you used. HMRC may ask for copies.
If HMRC needs time to look into the query, it can postpone all or part of the bill, and it must tell you in writing how much, if any, is still payable. Otherwise the deadline on the letter still applies. At the end of the query, HMRC will either confirm the assessment, issue an amended one, or withdraw it. You cannot appeal to the tribunal until you have raised a query and received HMRC's final response. Once you have that response, you have 30 days from the date of the decision letter to appeal.
If you cannot pay on time
Do not ignore the letter. HMRC runs an online Simple Assessment payment plan service. More generally, it can agree monthly instalments, usually by Direct Debit, after looking at your income, spending and savings. It typically asks for around half of what you have left each month after essential bills. There is no fixed time limit on a payment plan, but interest runs on the unpaid tax, so paying faster costs less. If you neither pay nor agree a plan, HMRC can use its debt collection powers, which include collecting the debt from your wages or pension.
Sources: HMRC's guidance on understanding your Simple Assessment and paying your Simple Assessment bill, HMRC's July 2026 announcement, the payment plan guidance, and sections 28H, 31AA and 59BA of the Taxes Management Act 1970. See also our guides to the P800 tax calculation, the personal savings allowance and fixing a wrong tax code.
If your Simple Assessment does not match your records, or you get a bill every year and want to understand why, Acumon's private client tax team can check the calculation and deal with HMRC for you.