P800 Tax Refund UK Guide 2025
Last updated: February 2026
Received a P800 from HMRC? This complete guide explains exactly what the letter means, how to claim your refund in minutes, and what to do if your P800 shows an underpayment instead. Do not lose part of your refund to a tax agent — claim it yourself for free.
P800 Refund Timeline Checker
Check when to expect your P800 and how quickly you can receive your refund.
What Is a P800 Tax Calculation?
A P800 is an official letter from HMRC (His Majesty's Revenue and Customs) that shows your complete tax picture for a finished tax year. HMRC produces P800 calculations after reconciling all the income and tax data they have received from employers, pension providers, banks, and government departments.
The P800 compares:
- The total tax you actually paid through PAYE throughout the year
- The total tax you should have paid based on all your income and allowances
The result is either a refund notice (you paid too much tax) or an underpayment notice (you paid too little tax). The vast majority of P800s — roughly 70% — show a refund.
When Does HMRC Send P800 Letters?
HMRC runs its annual end-of-year reconciliation process from July to November following the end of the tax year (which always ends on 5 April). P800 letters are sent in batches:
| Tax Year | Year Ended | P800 Sent | Deadline to Claim Refund Online |
|---|---|---|---|
| 2024/25 | 5 April 2025 | September – November 2025 | 45 days after receipt |
| 2023/24 | 5 April 2024 | September – November 2024 | 45 days after receipt |
| 2022/23 | 5 April 2023 | September – November 2023 | Claim via Personal Tax Account |
| 2021/22 | 5 April 2022 | September – November 2022 | Deadline: 5 April 2026 |
If you have not received a P800 but believe you are owed a refund, you can proactively check via your HMRC Personal Tax Account. HMRC's reconciliation process does not catch every case, and it is worth checking yourself.
What Triggers a P800 Tax Calculation?
You are more likely to receive a P800 if any of the following applied during the tax year:
- Multiple jobs: Having more than one job where your personal allowance was allocated to one employer but both jobs paid you
- Emergency tax code: Starting a new job on a W1/M1 or BR emergency code
- Changing jobs: Moving employers mid-year where your cumulative tax calculation was disrupted
- State Pension increase: An increase to the State Pension pushes your total income slightly higher than your tax code accounted for
- Bank or savings interest: Interest that exceeds your Personal Savings Allowance (£500 for higher rate, £1,000 for basic rate in 2025/26)
- Leaving work: Stopping work mid-year means you used less of your personal allowance than your code assumed
- Company benefits: A car, fuel, or health benefit that was over- or under-estimated
- Pension income: Starting to receive a pension without an accurate tax code being applied from day one
P800 Refund: How to Claim Your Money
If your P800 shows you are owed a refund, here is exactly what to do:
Check the P800 Letter
Read the letter carefully. Confirm the refund amount and the tax year it relates to. Check that the income figures shown match your payslips and P60. If anything looks wrong, call HMRC before claiming.
Claim Online (Fastest Method)
Visit gov.uk/claim-tax-refund or log in to your HMRC Personal Tax Account. Click “Claim a refund” and follow the instructions. You will need your bank sort code and account number. HMRC pays the refund within 5 working days directly to your bank account.
Wait for Cheque (Slower Method)
If you do not claim online within 45 days, HMRC automatically sends a cheque to your last known address. The cheque takes approximately 21 days to arrive. Make sure your address is up to date on your Personal Tax Account.
Cash or Deposit the Cheque
HMRC cheques are valid for 6 months from the date printed on them. Cash or deposit it promptly. If it expires, contact HMRC to request a replacement.
P800 Underpayment: When You Owe HMRC
If your P800 shows an underpayment (you paid too little tax), do not panic. HMRC rarely demands immediate payment for underpayments identified via a P800. Instead, they use a graduated collection approach:
Underpayments Under £3,000
HMRC adjusts your PAYE tax code for the following tax year to collect the underpayment gradually. For example, if you owe £600, your code number may be reduced by 60 (reducing your tax-free income by £600), resulting in approximately £120 more tax per month over 5 months, or spread over the whole year.
Underpayments Between £3,000 and £30,000
HMRC may ask you to pay directly, either in a lump sum or via self-assessment. If you cannot afford to pay, contact HMRC immediately to set up a Time to Pay arrangement — they are generally flexible.
Underpayments Over £30,000
For significant underpayments, HMRC will likely open a formal investigation or require payment via self-assessment. Professional tax advice is recommended at this level.
If You Disagree with the Underpayment
You have 60 days from the date of the P800 to dispute it. Call HMRC on 0300 200 3300 or respond in writing. Common reasons for incorrect underpayment notices include: pension lump sum taxed at source already, Gift Aid donations not accounted for, or income figures that include non-taxable amounts.
Checking if You're Owed a Refund Without a P800
HMRC does not always send a P800 even when you have overpaid tax. The system is not infallible. Here is how to proactively check whether you are owed money:
- HMRC Personal Tax Account: Log in at gov.uk/personal-tax-account to see your tax history, current year estimates, and whether any refunds are flagged.
- Review your P60: Compare the total tax paid on your P60 with what you should have paid based on your income and allowances. Use our Income Tax Calculator to check.
- Check previous years: You can claim for up to 4 previous tax years. Use HMRC's “Check if you paid the right tax” tool online.
- Contact HMRC: If you suspect you are owed a refund and cannot find it online, call 0300 200 3300 and request a review for specific tax years.
Common scenarios where people are owed refunds but never receive a P800 include: people who were on emergency tax codes for only part of a year, employees who received redundancy pay part of which was taxable, and people who made significant pension contributions that reduced their taxable income.
The 4-Year Time Limit for Claiming Refunds
HMRC imposes a strict 4-year time limit on income tax refund claims. After this deadline, the right to claim lapses permanently and HMRC will not make exceptions.
For the 2025/26 tax year, the years you can still claim for are:
| Tax Year | Claim Deadline | Status |
|---|---|---|
| 2021/22 | 5 April 2026 | Expires soon! |
| 2022/23 | 5 April 2027 | Open |
| 2023/24 | 5 April 2028 | Open |
| 2024/25 | 5 April 2029 | Open |
Frequently Asked Questions
What is a P800 tax calculation?+
A P800 is a letter from HMRC sent after the tax year ends. It shows your total income and tax paid versus what you should have paid, resulting in either a refund or an underpayment notice. It is sent between September and November of the following tax year.
How do I claim my P800 refund online?+
Log in to your HMRC Personal Tax Account at gov.uk/personal-tax-account. Navigate to 'Check if you paid the right amount of tax' and follow the prompts to claim. You will need your bank details. HMRC pays the refund within 5 working days. Do not use a third-party tax refund company.
How long does a P800 refund take?+
Claiming online: 5 working days to your bank. Not claiming online: HMRC sends a cheque automatically after 45 days, which takes 21 days to arrive. Total for cheque route: approximately 10 weeks from P800 issue date. Online claiming is much faster and more reliable.
What triggers a P800 tax calculation?+
Common triggers include multiple jobs, emergency tax codes, stopping work mid-year, State Pension increases, savings interest exceeding your allowance, company benefits changes, and changing employers. Any event that causes a mismatch between your tax code and actual income can trigger a P800.
Should I use a tax refund company?+
No. Tax refund companies charge 25-40% of your refund plus VAT for work you can do yourself for free in 5 minutes at gov.uk. Some use assignments of income (power of attorney) that allow them to receive all future refunds. HMRC has warned consumers about these companies. Always claim directly.
What if my P800 shows an underpayment?+
If you owe less than £3,000, HMRC collects it via your tax code next year, spread over 12 months. Larger amounts may require direct payment. If you disagree with the underpayment, contact HMRC within 60 days with evidence. HMRC offers Time to Pay arrangements if you cannot afford to pay immediately.
How far back can I claim overpaid tax?+
4 years. In 2025/26, you can claim for 2021/22 (deadline 5 April 2026), 2022/23, 2023/24, and 2024/25. The 2021/22 deadline is approaching very soon. Check your Personal Tax Account or call HMRC now if you suspect you overpaid in that year.