HMRC P800 letter explained
HMRC thinks you paid the wrong amount of tax last year. Here's how to check it and what to do next.
Last checked: 18 October 2026 · Written by Ivan S., finance professional
What this letter means
Most people pay tax automatically through their wages or pension. After the tax year ends, HMRC compares what you paid with what it thinks you should have paid. If the two don't match, you get a P800.
It goes one of two ways: you've paid too much and you're owed a refund, or you've paid too little and HMRC wants it back.
What to do
- Check the figures first. Compare the income and tax on the P800 with your P60 or P45. HMRC's calculation is only as good as the information it has, and it is sometimes wrong.
- If you're owed a refund: the letter tells you whether to claim it online through your personal tax account or whether a cheque is on its way. If it says a cheque is coming, you don't need to do anything.
- If you owe tax: HMRC will usually collect it by changing your tax code for the following year, so it comes out of your pay in small amounts. For larger amounts, HMRC will contact you about how to pay.
- Keep the letter. You may need it if your tax code changes or you query it later.
If you think it's wrong
Contact HMRC as soon as you can and explain which figure is wrong. Common causes are a job or pension HMRC didn't know had ended, estimated savings interest, or work expenses that weren't included.
If you fill in a Self Assessment tax return, tell HMRC; you'll usually settle the year through your return instead.
Watch out for refund scams
Emails and texts saying "you're due a tax refund, click here" are scams. A genuine P800 arrives by post or appears in your personal tax account.
Still not sure what yours says?
Snap a photo and we'll explain your exact figures and draft a reply to HMRC if you need one.
Explain my letterThis is general information, not tax advice. Letter Sorted is independent and not affiliated with HMRC.