A P800 is HMRC's tax calculation letter. It is sent to employees and pensioners whose PAYE deductions for the last tax year did not match the tax actually due. If it says you are due a refund, you either claim it online and are paid within 5 working days, or HMRC sends a cheque automatically within 14 days of the letter date. The letter tells you which. P800s for a tax year are sent between June and the following March, so letters for 2025/26 are arriving now.
What a P800 is, and who gets one
After each tax year ends on 5 April, HMRC reconciles the pay, pensions, benefits and tax reported to it under PAYE. If the tax deducted was too much or too little, it issues a P800. You will only get one if you are employed or receive a pension. If you are registered for Self Assessment, any overpayment or underpayment is dealt with through your return and you will not receive a P800.
HMRC's guidance on overpayments lists the usual reasons:
- Wrong tax code. Often because HMRC had out-of-date information about your income or benefits;
- Changing jobs. Finishing one job and starting another, and being paid by both in the same month;
- Starting to receive a workplace pension. Particularly in the first year a pension is paid;
- Benefits. Receiving Employment and Support Allowance or Jobseeker's Allowance during the year.
A P800 is an informal calculation, not an assessment. HMRC's own PAYE manual describes it as having "no statutory force". That is why checking it, and challenging it if the figures are wrong, is straightforward.
How to claim a P800 tax refund
The letter states whether you can claim online or will get a cheque.
If it says you can claim online. Use HMRC's online service to have the money paid by bank transfer or to request a cheque. You need:
- The P800 reference number. It is printed on the letter;
- Your National Insurance number.
You can also claim through your personal tax account or the HMRC app if you have a UK bank account, or by contacting HMRC. Bank transfers claimed online arrive within 5 working days. A cheque you ask for takes up to 6 weeks.
If it says you will get a cheque. You do not need to do anything. The cheque is posted within 14 days of the date on the letter. If you are owed tax for more than one year, you get a single cheque for the total.
Checking the calculation before you accept it
A refund is welcome, but the P800 is only as good as the data behind it. Check these points against your payslips, P60 and P45:
- Pay and tax figures. Each employment and pension should match your P60 or P45. Watch for a job counted twice, or an employer's figures for the wrong year;
- Benefits in kind. Company car and medical insurance figures should match your P11D or payrolled benefits;
- Allowances. Check the Personal Allowance (£12,570 standard for 2025/26) and any Marriage Allowance or expenses HMRC has applied;
- Taxable state benefits. State Pension, Jobseeker's Allowance or Employment and Support Allowance should be at the correct amounts.
If something is wrong, contact HMRC and tell it which amounts are incorrect and what they should be. If HMRC agrees, it issues a new calculation; if not, it explains why. Correct a wrong refund before you spend it, because an inflated refund can be clawed back later through your tax code.
If the P800 says you owe tax
Underpayments are usually collected through your tax code, spread over 12 months from the start of the following tax year (6 April). This happens automatically if:
- You pay tax through PAYE. On wages, salary or a pension;
- Your income is enough. You earn enough above your Personal Allowance to cover the extra tax;
- The amount is under £3,000. HMRC's PAYE manual confirms that underpayments of less than £3,000 are coded out automatically.
You can choose to pay the whole amount before the next tax year starts instead. If the tax cannot be collected through your code, for example because you owe £3,000 or more, HMRC issues a Simple Assessment instead. For a 2025/26 Simple Assessment letter dated before 31 October 2026, payment is due by 31 January 2027. For later letters, payment is due within 3 months of the letter date. Any query must be raised within 60 days.
Spotting P800 refund scams
Fake "tax refund" messages are among the most common HMRC-themed scams. HMRC's scam guidance says that a message offering a refund, tax rebate or grant is a warning sign. HMRC will never use social media to offer a rebate. Do not click links in texts that offer a refund in exchange for personal or bank details. A genuine P800 arrives as a letter, or in your personal tax account, with a reference you can use on gov.uk directly. Forward suspicious texts to 60599 and emails to [email protected].
No P800 but think you are owed money?
Not every overpayment produces a letter. Refunds for unclaimed employment expenses, emergency tax on a pension withdrawal, or tax on savings interest often have to be claimed. HMRC's "check how to claim a tax refund" tool points you to the right route. The general time limit is 4 years from the end of the tax year, so claims for 2022/23 must be made by 5 April 2027. Note that employees can no longer claim the working from home deduction from 2026/27, although earlier years remain open; see our working from home allowance guide.
If your affairs are more complex than one job, for example with several employments, a pension and rental income, a P800 may not reflect the full picture. Registering for Self Assessment may be the more accurate route. Acumon's income tax return team checks HMRC calculations and handles refund claims, and our PAYE services help employers get tax codes right in the first place.