HMRC P800 Letter Guide 2026 — How to Claim Your Tax Refund or Pay What You Owe
An HMRC P800 (Tax Calculation) letter tells you if you've overpaid or underpaid tax. If you're owed a refund, you can claim it online within 45 days. If you owe tax and it's under £3,000, HMRC usually collects it through your next year's PAYE tax code.
What is a P800?
A P800 is an official document from HMRC called a Tax Calculation. It is sent to employees and pensioners who are taxed through the PAYE (Pay As You Earn) system when HMRC's records show a discrepancy between the tax you should have paid and the tax you actually paid during the tax year.
The P800 is not a penalty or a formal demand — it is a reconciliation. Think of it as HMRC checking your tax account at the end of the year and telling you whether the balance is in your favour or theirs.
HMRC generates P800s using information gathered from:
- Your employer's PAYE submissions (RTI — Real Time Information)
- Pension provider records
- Bank and building society interest reports (third-party data)
- Benefits-in-kind records (P11D)
- HMRC's own records of any adjustments made to your tax code during the year
Not everyone receives a P800. If your tax affairs are straightforward and the PAYE system has correctly deducted the right amount throughout the year, you will not receive one.
When are P800s issued?
The tax year ends on 5 April. HMRC processes its reconciliation work in the months that follow, typically sending P800s between June and November of the same calendar year.
For the 2025/26 tax year (ended 5 April 2026), P800s are expected to be sent between June and November 2026.
The timing is staggered — HMRC does not send all P800s simultaneously. Yours may arrive any time during this window. If you are expecting a refund and have not received a P800 by November, you can check your Personal Tax Account (gov.uk/personal-tax-account) or contact HMRC directly.
Scenario 1: You are owed a refund
If the P800 shows that HMRC owes you money — meaning you paid too much tax through PAYE — you have options for how to receive it.
Claim online (fastest)
Log in to your Personal Tax Account at gov.uk/personal-tax-account within 45 days of the date on the P800. You can request the refund be paid directly to your bank account. Refunds claimed online are typically processed within 5 working days.
You will need:
- Your National Insurance number
- Government Gateway login credentials (or an alternative identity verification method)
- Your bank sort code and account number
Automatic cheque (if you do not claim online)
If you do not claim your refund online within 45 days, HMRC will automatically send a cheque to your last known address, usually within 60 days of the P800 being issued. The cheque is payable to you personally and valid for 3 months from the date of issue.
What if I no longer live at the address on the P800?
If HMRC does not hold your current address, the cheque may go to a previous address. Update your address via your Personal Tax Account as soon as possible. If you believe a cheque has been sent to the wrong address, contact HMRC on 0300 200 3300.
Scenario 2: You owe tax to HMRC
If the P800 shows you owe tax, how HMRC collects it depends on the amount.
Underpayment up to £3,000 — collected through your tax code
For most underpayments up to £3,000, HMRC will add the debt to your PAYE tax code for the following tax year. This means your tax-free personal allowance is reduced, so you pay slightly more tax each month from your salary or pension — spreading the repayment over 12 months without requiring an upfront lump sum.
Example: You owe £600 from the 2025/26 tax year. HMRC reduces your 2026/27 personal allowance by £3,000 (£600 / 20% basic rate tax = £3,000 coding adjustment). Over the year, you pay £50/month extra in PAYE tax, recovering the full £600.
Your new tax code will reflect this adjustment — look for a lower number than 1257L (the standard code for those using their full Personal Allowance).
Underpayment over £3,000 — direct payment required
If you owe more than £3,000, or if collection through your tax code is not possible (e.g. you are leaving employment, are a pensioner with a small pension), HMRC will contact you separately. This may require you to:
- Set up a Time to Pay arrangement (an instalment plan agreed directly with HMRC)
- Register for Self Assessment to pay the balance on account
- Pay by direct bank transfer (bank transfer details are provided in the P800 or accompanying letter)
If you receive a P800 showing a large underpayment and cannot afford to pay it in full, contact HMRC as early as possible to discuss a Time to Pay arrangement. HMRC does not automatically apply interest on underpayments recovered through the tax code, but interest does apply if direct payment is late.
Common reasons for underpayment
HMRC's PAYE system is largely automated but can produce incorrect tax codes in several common circumstances:
| Reason | What happened |
|---|---|
| Two jobs at the same time | Personal Allowance may have been applied to both — resulting in under-deduction on one job |
| Emergency tax code | Applied when starting a new job without a P45 — often deducts too much or too little |
| Savings interest above PSA | Banks report interest to HMRC; if not factored into your code, tax is underpaid |
| State Pension + employment | State Pension is not deducted via PAYE — it relies on your other income carrying the tax burden |
| Company car benefit | P11D values not correctly coded into PAYE during the year |
| Pension drawdown income | Pension providers sometimes deduct at emergency rates; PAYE reconciliation corrects this |
| Benefits in kind | Medical insurance, gym memberships, etc. taxed via P11D — may not have been coded correctly |
Common reasons for overpayment (refund)
| Reason | What happened |
|---|---|
| Left job mid-year | PAYE assumed you would work the full year; your actual income was lower than projected |
| Emergency tax code applied incorrectly | Month 1 basis deducted more tax than necessary |
| Pension lump sum (emergency rate) | Pension providers often withhold 45% emergency rate on lump sums; actual rate is lower |
| Received a refund from employer but code not updated | Duplicate deduction |
| Personal Allowance not applied | Wrong tax code used by employer |
How to dispute a P800
If you believe your P800 is incorrect, do not ignore it. Take the following steps:
- Gather evidence: P60 from your employer, payslips, bank statements showing savings interest, any correspondence with HMRC about tax code changes.
- Contact HMRC within 60 days: Call 0300 200 3300 (income tax helpline) or write to the address shown on the P800. Explain the discrepancy and provide supporting documents.
- Check your Personal Tax Account: Your tax account at gov.uk shows your income sources and the data HMRC holds. Check this matches your actual situation.
- Keep records: Note the date of your call, the name of the HMRC officer you spoke with, and any reference numbers provided.
HMRC will review and, if your dispute is upheld, issue a revised P800 or close the underpayment. There is no automatic right of appeal against a P800 (it is not a formal assessment), but HMRC has a complaints process if the dispute is not resolved to your satisfaction.
P800 vs Self Assessment
HMRC uses P800s for taxpayers whose affairs are relatively straightforward — single employer, standard income sources, no complex reliefs. If your situation is more complex, HMRC may require you to complete a Self Assessment tax return instead of issuing a P800.
You will need to file Self Assessment if:
- Your total income exceeds £100,000
- You have self-employment income over £1,000
- You have rental income over £2,500
- You have untaxed income not collected through PAYE (e.g. dividends above £500)
- You have capital gains above the Annual Exempt Amount (£3,000 in 2026/27)
- You are a director of a limited company
If you receive a P800 but you think you should be filing Self Assessment (because you have income not captured in the P800), contact HMRC to register.
Related calculators
The income tax calculator helps you independently verify what your income tax liability should have been — useful for checking whether a P800 figure looks correct.
The take-home pay calculator lets you see how a tax code change (to collect an underpayment) will affect your monthly net pay.
Frequently asked questions
What is an HMRC P800?
A P800 (Tax Calculation) is a letter or document sent by HMRC after the end of the tax year to tell you whether you have paid too much or too little income tax through PAYE. It is not a penalty notice — it is simply HMRC's reconciliation of your PAYE account.
When do I receive a P800?
HMRC typically sends P800 letters between June and November following the end of the tax year (which runs to 5 April). So for the 2025/26 tax year, P800s are usually issued from June to November 2026. Not everyone receives one — only those whose PAYE records show a discrepancy.
I have a P800 showing I am owed a refund — how do I claim it?
If you are owed a refund, claim it online through your Personal Tax Account at gov.uk/personal-tax-account. You have 45 days to claim online. After 45 days, HMRC will issue a cheque automatically (usually within 60 days of the P800 being issued).
What if I owe tax according to my P800?
If you owe up to £3,000, HMRC will usually add it to your tax code for the following year — spreading the collection over 12 months through reduced PAYE. If you owe more than £3,000 (or if collection through your code is not possible), HMRC will contact you separately and may require direct payment.
Can I dispute a P800 if I think it is wrong?
Yes. Contact HMRC within 60 days of receiving the P800. You can call HMRC's income tax helpline (0300 200 3300) or write to the address on the letter. Provide any evidence of correct tax paid (P60, payslips, bank statements). HMRC will review and issue a corrected calculation if appropriate.
Why would I have underpaid tax through PAYE?
Common reasons include: starting or ending employment mid-year, having two jobs simultaneously, receiving untaxed income (savings interest, pension, rental income), employer using the wrong tax code, or incorrectly claiming tax relief on expenses.
Do I need to complete a Self Assessment if I receive a P800?
Not necessarily. P800s are used for straightforward PAYE cases. If your tax affairs are complex (e.g. income over £100,000, self-employment income, large savings interest, or rental income), HMRC may instead require you to register for Self Assessment rather than issuing a P800.
Try the calculators
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