Written by Hammad Rasool MAAT·AAT licensed accountant·Updated November 2026

What a P800 is

HMRC sends a tax calculation letter, known as a P800, if you paid too much or too little Income Tax by the end of the tax year on 5 April. You only get one if you are employed or receive a pension. If you are registered for Self Assessment you will not get a P800, because your tax return settles the bill instead.

The letters go out between June and March following the end of the tax year, so one can arrive many months after the year it relates to.

Why you might get one

GOV.UK lists the usual reasons:

  • You were put on the wrong tax code, for example because HMRC had the wrong information about your income.
  • You finished 1 job, started a new one and were paid by both in the same month.
  • You started receiving a pension at work.
  • You received Employment and Support Allowance or Jobseeker's Allowance.

If the letter says you are due a refund

The letter tells you how you will be paid.

  • Claim online: you can claim by bank transfer using your P800 reference and your National Insurance number. The money is sent within 5 working days of an online claim.
  • Request a cheque: a cheque you ask HMRC for can take 6 weeks.
  • Automatic cheque: if the letter says HMRC will send a cheque, you do not need to claim. It should arrive within 14 days of the date on the letter.
Scam warning: a genuine P800 arrives by post or in your HMRC online account. HMRC does not send refund offers by text or email with a link. If in doubt, sign in to your Personal Tax Account directly and check.

If the letter says you owe tax

HMRC will usually collect the tax by changing your tax code, so a little extra comes out of your pay or pension each month. This is normally spread over 12 months starting from the next tax year. It happens automatically if you pay Income Tax through an employer or pension provider, you earn enough over your Personal Allowance to cover it, and you owe less than £3,000.

If HMRC cannot collect it through your tax code, it will write to tell you how to pay. You can also choose to pay it off early.

Check the figures before you accept them

A P800 is a computer calculation based on what employers, pension providers and banks have reported. Compare it with your P60, your P45 if you changed jobs, your final payslips and any benefit in kind forms. The most common errors we see are an old job still showing as live, estimated savings interest and a company benefit that ended.

Example

Aisha changed jobs in October. Her old employer was slow to send her leaving details, so HMRC treated both jobs as running to the end of the year and issued a P800 showing £640 owed. Once the correct leaving date was given to HMRC, a new calculation was issued and the amount owed fell to nil.

If you think the P800 is wrong

Contact HMRC and tell them which figures are wrong and what they should be. If HMRC agrees, it will send a new calculation. If it does not agree, it will explain why. Do not simply ignore the letter, because the tax code change will go ahead on the figures HMRC holds.

Common questions

Is a P800 a fine?
No. It is a calculation showing whether you paid too much or too little tax. There is no penalty attached to it.
How long does a P800 refund take?
GOV.UK says the money is sent within 5 working days if you claim online by bank transfer. A cheque you request can take 6 weeks. If the letter says a cheque will be sent automatically, it should arrive within 14 days of the date on the letter.
Why did I get a P800 when I am on PAYE?
PAYE collects tax as the year goes on using your tax code. If the code was wrong, or your circumstances changed part way through the year, the total can end up too high or too low. The P800 corrects it.
Can I pay the tax I owe in one go?
Yes. You can pay the amount early instead of having it collected through your tax code.

Checked against GOV.UK on 10 November 2026: Tax overpayments and underpayments, If you are due a refund, If you owe tax.

About the author

Hammad Rasool MAAT is an AAT licensed accountant based in Bolton. TaxTune Accountants looks after sole traders, landlords, contractors and limited companies in Bolton, Wigan, Bury, Salford, Oldham, Stockport and Manchester, and online across the UK.