P800 Refund: What the HMRC Letter Means and When You're Paid

A P800 is HMRC's tax calculation letter. It tells an employee or pensioner that they paid too much or too little tax in a tax year that has ended. HMRC sends them between June and March of the following year. A refund claimed online is paid within 5 working days; underpayments under £3,000 are usually collected through your tax code.

The letter is only sent if you are employed or get a pension. If you are registered for Self Assessment, your return does the reconciliation instead and you will not get a P800 (HMRC).

What a P800 shows

HMRC works out the tax you should have paid on the income it knows about, and compares it with the tax your employers and pension providers deducted. The letter shows:

• the income from each job or pension, as reported by your employer through payroll;
• any taxable benefits, such as a company car reported on a P11D;
• other income HMRC knows about, such as taxable State benefits;
• the allowances used;
• the tax you should have paid, the tax actually taken, and the difference.

Why people get a P800

HMRC lists the common reasons as being on the wrong tax code, finishing one job and starting another and being paid by both in the same month, starting a workplace pension, or receiving Employment and Support Allowance or Jobseeker's Allowance (HMRC). In practice that includes:

• an emergency code such as 1257L M1 or 0T for part of the year after a job change;
• a second job taxed on BR or D0 when the allowance was not being used elsewhere;
• stopping work part-way through the year, leaving some Personal Allowance unused;
• a benefit in kind that ended but stayed in your tax code, or started but was never added.

If your P800 says you are due a refund

If the letter says you can claim online

Use HMRC's online service with the reference from your letter and your National Insurance number. You can choose a bank transfer, paid within 5 working days, or ask for a cheque, paid within 6 weeks. You can also claim through your personal tax account or the HMRC app if you have a UK bank account (HMRC).

If the letter says you will get a cheque

You do not need to do anything. The cheque should arrive within 14 days of the date on the letter. If you are owed tax for more than one year, you get one cheque for the total.

Worked example: a job change in 2025/26

You earned £30,000 in a single job in 2025/26 on code 1257L, then changed jobs. Your new employer used 0T for the last three months before HMRC issued a normal code.

• Tax you owed for the year: (£30,000 − £12,570) × 20% = £3,486.
• On 0T the new employer taxed all of its pay without a Personal Allowance. For the three months the 0T code was used, the allowance you missed was £12,570 × 3/12 = £3,142.50, and 20% of that is £628.50 of tax taken that you did not owe.
• The P800 shows the overpayment and how to claim it. Claimed online, it is paid within 5 working days.

Figures use the 2025/26 Personal Allowance of £12,570 and 20% basic rate (HMRC). The exact overpayment on a real P800 also depends on how your old employer's P45 was used.

If your P800 says you owe tax

HMRC normally collects it by changing your tax code, in equal instalments over 12 months from the start of the next tax year. This happens automatically if you pay tax through an employer or pension, have enough income above your Personal Allowance to cover it, and owe less than £3,000. You can pay it early if you prefer (HMRC).

If HMRC cannot collect it through your code, or you owe more than £3,000, you get a Simple Assessment letter instead. For a 2025/26 bill sent before 31 October 2026, the deadline is 31 January 2027. For one sent on or after 31 October 2026, you have 3 months from the date of the letter (HMRC). You can pay in instalments as long as the full amount is paid by the deadline.

Worked example: collecting £600 through your code

You owe £600 for 2025/26. HMRC will reduce your 2026/27 allowance so that the extra tax works out at £600 over the year. For a basic-rate taxpayer that is a £3,000 reduction in allowance (£3,000 × 20% = £600), turning 1257L into 957L, which is £50 a month more tax.

If you think the P800 is wrong

1. Compare the pay and tax figures with your P60s and final payslips for that year.
2. Compare any benefit figures with your P11D.
3. Check the income HMRC holds in your personal tax account.
4. Tell HMRC which amounts you think are wrong and what they should be. Call 0300 200 3300 (HMRC).
5. If HMRC agrees, it sends a new calculation. If not, it explains why.

P800, Simple Assessment and Self Assessment

• P800: the standard year-end calculation for people taxed through PAYE.
• Simple Assessment: a bill HMRC works out for you when tax cannot be collected through your tax code, when you owe more than £3,000, or when you have to pay tax on your State Pension.
• Self Assessment: if you are registered, your return replaces both, and your bill is adjusted for any over- or underpayment.

Do you need a refund company?

No. HMRC's online claim takes a few minutes with the reference on the letter, and HMRC does not charge for it. A company that files the same claim for you will take a share of the refund.

Frequently asked questions

When do P800 letters arrive?

HMRC sends P800 tax calculation letters between June and March after the end of the tax year. For the 2025/26 tax year that means between June 2026 and March 2027. You only get one if you are employed or get a pension and are not in Self Assessment.

How long does a P800 refund take to be paid?

If you claim online by bank transfer, HMRC sends the money within 5 working days. If you ask for a cheque online, it takes up to 6 weeks. If your letter says a cheque will be sent automatically, it should arrive within 14 days of the date on the letter.

What happens if my P800 says I owe HMRC?

If you owe less than £3,000 and pay tax through an employer or pension, HMRC usually collects it through your tax code over 12 months from the next tax year. If it cannot, or you owe more than £3,000, you get a Simple Assessment letter with a payment deadline.

Why did I get a P800 refund?

Common causes are being on the wrong tax code, an emergency code after a job change, being paid by two employers in the same month, starting a workplace pension, or stopping work part-way through the year so some Personal Allowance went unused.

Can I challenge a P800 calculation?

Yes. Check the pay, tax and benefit figures against your P60s, final payslips and P11D, then contact HMRC and tell it which amounts are wrong and what they should be. If HMRC agrees, it issues a new calculation.

What if I never received a P800?

It may mean you paid the right tax, that you are in Self Assessment, or that HMRC has not yet run the calculation for your record. If you think you have overpaid and no letter arrives, use HMRC's claim a tax refund service.

Sources

All sources were opened and checked by PayslipIQ on 21 September 2026.

• HMRC (GOV.UK): Tax overpayments and underpayments. When letters are sent and why. Verified 21 Sep 2026.
• HMRC (GOV.UK): If your P800 says you're due a refund. 5 working days, 6 weeks and 14 days. Verified 21 Sep 2026.
• HMRC (GOV.UK): If your P800 says you owe tax. Collection through the tax code and the £3,000 limit. Verified 21 Sep 2026.
• HMRC (GOV.UK): Pay your Simple Assessment tax bill. Payment deadlines. Verified 21 Sep 2026.
• legislation.gov.uk: Taxes Management Act 1970, Schedule 1AB, paragraph 3. The 4-year time limit for overpayment claims. Verified 21 Sep 2026.
• HMRC (GOV.UK): Income Tax rates and Personal Allowances. Verified 21 Sep 2026.
• HMRC (GOV.UK): Income Tax: enquiries. Helpline 0300 200 3300. Verified 21 Sep 2026.

Disclaimer

PayslipIQ provides educational guidance based on published HMRC rules. It is not regulated tax advice. A P800 depends on the figures your employers, pension providers and DWP sent HMRC. If they are wrong, the calculation will be wrong, so check them before you rely on it.