What is a P800 tax calculation?

What a P800 is

A P800 is a tax calculation from HM Revenue and Customs (HMRC). It looks back at the last tax year (6 April to 5 April) and checks whether the right amount of Income Tax was taken through PAYE. PAYE means tax taken from your wages or pension before you are paid.

Some people get a Simple Assessment letter instead. It does a similar job.

Who gets one

You may get a P800 if you are employed or get a pension, and you are not registered for Self Assessment. If you are in Self Assessment, any difference is sorted out in your tax return instead.

Letters are sent between June and March after the end of the tax year. A P800 for 2025/26 (the year to 5 April 2026) could arrive any time from June 2026 to March 2027.

Why you might get one

Common reasons are:

• you were on the wrong tax code, for example because HMRC had the wrong information about your income
• you finished one job, started a new one and were paid by both in the same month
• you started getting a pension from work
• you got Employment and Support Allowance or Jobseeker's Allowance

If HMRC owes you money

Your P800 will say how to get your refund.

To claim online, you need the reference number from your P800 and your National Insurance number. You can also claim through your Personal Tax Account or the HMRC app if you have a UK bank account. If HMRC sends you a cheque and you are owed money for more than one year, you get a single cheque for the whole amount.

If you owe tax

HMRC will usually collect it by changing your tax code. This usually spreads the amount in equal parts over 12 months, starting at the beginning of the next tax year. This normally happens if:

• you pay tax through an employer or pension provider
• you earn enough above your Personal Allowance
• you owe less than £3,000

If HMRC cannot collect it this way, it will write to tell you how to pay. You can also choose to pay early, before the next tax year starts.

If you think your P800 is wrong

Contact HMRC. Tell them which amounts you think are wrong and what they should be. HMRC will then either send you a new calculation or explain why it thinks the original one is right.

Things to know

• It applies across the UK. The P800 process is the same in England, Scotland, Wales and Northern Ireland, though Scottish and Welsh taxpayers' figures use their own Income Tax rates.
• Not had one? If you think you paid too much tax, you can still contact HMRC or claim a refund yourself.

Related guides

• How do I claim a tax refund?
• What does my tax code mean?
• What is the HMRC app?
• How do I spot and report an HMRC scam?
• What is a P60?

Where this comes from

• Tax overpayments and underpayments (GOV.UK)
• If you're due a refund (GOV.UK)
• If you owe tax (GOV.UK)
• Claim an Income Tax refund (GOV.UK)