P800 tax calculation: when it arrives and what to do with it

Where to find your P800 tax calculation letter

What it looks like

A letter headed as a tax calculation for one tax year, comparing the tax you should have paid on your income from jobs and pensions with the tax actually taken, and showing whether you're due a refund or owe tax.

If you've lost it

• You can also claim a refund through your personal tax account or the HMRC app, if you have a UK bank account.
• If the letter says you'll get a cheque automatically, you don't need to do anything: it arrives within 14 days of the date on the letter.
• Otherwise contact HMRC and ask about your tax calculation.

Why you got one

At the end of the tax year HMRC compares your final income with the tax you paid. If they don't match, you get a P800, or sometimes a Simple Assessment letter instead. Common reasons include being on the wrong tax code, having two jobs paid in the same month, starting a workplace pension, or getting Employment and Support Allowance or Jobseeker's Allowance.

You only get a P800 if you're employed or get a pension. If you're registered for Self Assessment, your bill is adjusted through your return instead.

If it says you're due a refund

Claim using HMRC's online bank transfer service or request a cheque online, using the reference from the letter 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.

The money arrives within 5 working days if you claim online, or 6 weeks if you ask for a cheque. Some letters say a cheque will be sent automatically, in which case it arrives within 14 days of the date on the letter.

If it says you owe tax

HMRC usually collects underpaid tax by changing your tax code, so it comes out of your pay or pension in equal instalments over 12 months from the start of the next tax year. That happens automatically if you pay through an employer or pension provider, earn enough above your Personal Allowance to cover it, and the amount is under HMRC's limit for collecting through a tax code. Otherwise HMRC writes to you about how to pay. You can choose to pay early, before the next tax year starts.