Every year, HMRC sends out approximately 3 million P800 letters to UK taxpayers — with the average refund sitting at around £750. Yet despite being one of the most widely issued documents in the entire UK tax system, a surprising number of recipients have no idea what a P800 means, whether they need to do anything, or how to make sure they don’t lose money that is rightfully theirs. This comprehensive guide walks you through everything you need to know about the P800 tax calculation: how to claim your refund, what steps to take if you’ve underpaid, and how to keep yourself safe from scams targeting P800 recipients.
What Is a P800 Form?
A P800 is an official tax calculation letter issued by HM Revenue & Customs (HMRC). It is not a form you complete — rather, it is a document sent to you, either by post or through your HMRC online account, once HMRC has finished its end-of-year review of your Pay As You Earn (PAYE) records.
The P800 works by comparing two figures: the amount of Income Tax you actually paid during the tax year (deducted directly from your salary or pension by your employer or pension provider) against the amount HMRC believes you should have paid based on your total taxable income and personal allowances. When those two figures don’t match, HMRC notifies you of the difference through a P800.
On the official gov.uk website, this document is referred to as a tax calculation letter, though the term “P800” has become the standard shorthand in accountancy and tax advisory circles. It covers Income Tax only and applies exclusively to individuals taxed through PAYE. It does not cover National Insurance Contributions or Capital Gains Tax.
What Does a P800 Show?
Your P800 tax calculation letter will include:
- Your total gross income recorded by HMRC for the relevant tax year — covering all employment income, pension income, and applicable state benefits
- Your tax-free Personal Allowance for that year (£12,570 for 2025/26)
- Any taxable benefits in kind reported by your employer on form P11D
- Work expenses or tax reliefs already factored in
- The total Income Tax you paid through PAYE during the year
- HMRC’s own calculation of what you should have paid
- The resulting difference — either a refund owed to you (overpayment) or an amount owed to HMRC (underpayment)
Why Have I Received a P800? Common Reasons for Tax Overpayment
HMRC only issues a P800 when your tax position for the year turns out to be incorrect. In most cases, this is entirely routine and not the result of anything you’ve done wrong.
| Reason | Explanation |
|---|---|
| Emergency tax code applied | Starting a new job without a P45 can result in your employer placing you on an emergency tax code (such as 1257L W1/M1 or 0T), which often leads to overtaxation until HMRC corrects the code. |
| Multiple employments or pensions | Working for more than one employer at the same time — or receiving both a salary and a pension — can mean tax is deducted twice on income that should only have used the personal allowance once. |
| Leaving employment mid-year | If you left a job before the end of the tax year and didn’t transfer your code to a new employer, you may have paid more tax than necessary given your lower actual annual income. |
| Unclaimed work expenses | If you were entitled to tax relief on work-related costs (uniforms, professional subscriptions, tools, etc.) but never claimed during the year, HMRC may flag the overpayment at year-end. |
| Income lower than forecast | A drop in earnings mid-year may not have been reflected quickly enough in your tax deductions, with your employer continuing to deduct at a higher rate. |
| Late tax code changes | If HMRC updated your code partway through the year, the correction may not have arrived early enough to prevent overtaxation in the earlier months. |
| State benefits received | Certain state benefits — such as Jobseeker’s Allowance or carer payments — are taxable and can affect your overall tax calculation in ways that create discrepancies. |
How to Claim a P800 Tax Refund Online: Step-by-Step
Important update for 2026: Since 31 May 2024, HMRC has stopped issuing automatic repayments in most cases. If your P800 says you can claim online, you need to actively log in and submit a claim. A cheque will not automatically arrive unless your letter explicitly states one will be sent.
Method 1: Claim Online via gov.uk/p800refund (Fastest)
This is the quickest route and typically results in the money reaching your bank account within 5 working days.
- Find the 10-digit P800 reference number at the top of your HMRC letter.
- Go to gov.uk/p800refund in your browser. Before entering any personal details, check that the address ends in .gov.uk and that a padlock icon appears in the address bar.
- Click ‘Claim now’ and sign in using your Government Gateway user ID and password — or register for an account if you don’t already have one.
- Enter your National Insurance number and confirm that your total income matches the figure on your P800.
- Provide the sort code and account number for a UK bank account in your own name. HMRC will not transfer funds to a third-party account without written authorisation.
- Review the summary and submit your claim.
- Save the confirmation reference number shown at the end of the process.
Method 2: Claim via the HMRC App
The official HMRC app — available on both iOS and Android — also allows you to claim your refund. Log in with your Government Gateway credentials, navigate to your Personal Tax Account, and follow the prompts. The payment timescale is the same as the online method: typically 5 working days.
Method 3: Receive a Cheque Automatically
In certain circumstances, your P800 letter will state that HMRC will send a cheque automatically, with no action required from you. If this applies, the cheque should arrive within 14 days of the letter date. Where a refund spans more than one tax year, HMRC will typically issue a single combined cheque rather than separate ones.
Method 4: Contact HMRC by Phone
If online or app-based claiming isn’t an option for you, call the HMRC Income Tax helpline on 0300 200 3300 (Monday to Friday, 8am to 6pm) to request your refund by cheque. You’ll need your National Insurance number and personal details ready to verify your identity.
P800 Refund Timescales at a Glance
| Claim Method | Timescale | Payment Method |
|---|---|---|
| Online (gov.uk/p800refund) | 5 working days | Bank transfer |
| HMRC app | 5 working days | Bank transfer |
| Automatic cheque (issued by HMRC) | Within 14 days of letter date | Cheque by post |
| Phone request (cheque) | Up to 6 weeks | Cheque by post |
| During HMRC processing backlog periods | May be longer | Bank transfer or cheque |
What Should I Do If My P800 Shows I Have Underpaid Tax?
Discovering an underpayment on your P800 can feel unsettling, but HMRC deals with these situations in a measured and proportionate way. You will not face penalties simply because you underpaid through PAYE — this is typically the result of an employer or pension provider deducting the wrong amount, or your circumstances changing mid-year.
How HMRC Collects Underpaid Tax
For underpayments up to £3,000, HMRC usually recoups the amount by adjusting your tax code in the following tax year, spreading the cost across 12 months. For underpayments over £3,000, or if HMRC cannot collect through your code, you’ll receive a separate demand for payment.
Statute of limitations: HMRC can generally only pursue underpaid PAYE tax going back four tax years. Older underpayments arising from HMRC’s own error may be eligible for write-off under the ESC A19 concession, which can apply where the taxpayer could not reasonably have been aware of the underpayment at the time.
If paying the full underpayment immediately is not feasible, you can contact HMRC to discuss a Time to Pay arrangement, which allows you to clear the balance in instalments.
How Far Back Can You Claim a P800 Refund? The 4-Year Rule
HMRC allows overpaid tax to be claimed back for up to four complete tax years prior to the current one. Each tax year runs from 6 April to 5 April the following year. The current claim windows are:
| Tax Year | Claim Deadline | Status |
|---|---|---|
| 2021/22 (6 Apr 2021 – 5 Apr 2022) | 5 April 2026 | ⚠️ Deadline approaching — claim now |
| 2022/23 (6 Apr 2022 – 5 Apr 2023) | 5 April 2027 | Open |
| 2023/24 (6 Apr 2023 – 5 Apr 2024) | 5 April 2028 | Open |
| 2024/25 (6 Apr 2024 – 5 Apr 2025) | 5 April 2029 | Open |
Haven’t received a P800 but think you’re owed money? Log in to your HMRC Personal Tax Account and check your Income Tax summary. Alternatively, write directly to HMRC — mark the envelope ‘Repayment Claim’ and include your National Insurance number, personal details, and any supporting documents such as P60s or P45s.
What Should I Do If My P800 Is Wrong?
If the figures on your P800 don’t match your payslips, P60, or other income records, it’s important to raise this with HMRC promptly. The most common causes of an inaccurate P800 include:
- An employer or pension provider submitting incorrect figures to HMRC
- A benefit-in-kind (reported on form P11D) being included or omitted incorrectly
- A tax relief or allowance you’re entitled to being overlooked
- Income from a different tax year being attributed to the wrong period
How to Dispute a P800
- Gather your payslips, P60, P45, and any P11D your employer issued for the relevant year.
- Cross-reference each figure with what appears on the P800.
- If you identify a discrepancy, contact HMRC on 0300 200 3300 or write to HMRC with your supporting evidence.
Don’t ignore an underpayment notice you believe is wrong. HMRC will still attempt to collect through your tax code even if you take no action. Challenge it proactively.
Tip: Check Your Tax Code First
A significant proportion of P800 discrepancies stem from an incorrect tax code. You can view your current and historic tax codes in your HMRC Personal Tax Account at any time.
Watch out for two common problem codes:
- Emergency codes (e.g. 1257L W1/M1) — these treat each pay period as though you’ve had no previous income or tax in the year, often leading to overtaxation.
- BR (Basic Rate) — applies a flat 20% tax rate to all income with no personal allowance deducted, which almost always results in overpayment.
P800 vs P60: What’s the Difference?
These two documents are among the most frequently confused in the UK tax system. Here’s a clear breakdown:
| Feature | P800 | P60 |
|---|---|---|
| Issued by | HMRC | Your employer or pension provider |
| Purpose | Shows whether you overpaid or underpaid tax | Confirms your total pay and tax for the year |
| When issued | June to November (after year end) | By 31 May (after year end) |
| Contains | Tax calculation comparing expected vs actual tax paid | Gross pay, total Income Tax, NIC deducted |
| Action required? | Yes — claim refund or address shortfall | Keep as a record; use to verify P800 figures |
| Can you request it? | No — HMRC issues automatically if needed | From your employer if not received by 31 May |
| Used for what? | Triggering a refund or collection | Proof of income (e.g. mortgage applications, benefits) |
The simplest way to think about it: your P60 is your employer’s record of what happened during the year, while your P800 is HMRC’s independent audit of those same figures.
How to Spot a P800 Scam: Protecting Yourself
In the 12 months leading to January 2024, HMRC received over 200,000 scam reports — a 29% increase on the previous year. As of 2025 and 2026, fraudsters have grown more sophisticated, deploying AI deepfake technology and spoofed SMS messages to convincingly mimic genuine HMRC communications. Fake P800 refund messages remain one of the most commonly reported scam formats.
HMRC Will NEVER:
- Send a P800 refund notification by text message, WhatsApp, or email with a link to claim
- Request your bank details, card numbers, PIN, or passwords via text or email
- Demand immediate payment by gift card, cryptocurrency, or bank transfer to a private account
- Threaten arrest, legal action, or bailiffs without prior official written correspondence
- Transfer a refund to a third-party bank account without written authorisation from you
How to Verify a Genuine P800
A legitimate P800 will only ever appear in your HMRC Personal Tax Account online, or arrive by post to your registered home address. HMRC will never contact you about a P800 refund through social media, email, or messaging apps.
If you receive a suspicious email, forward it to phishing@hmrc.gov.uk. Report suspicious texts by forwarding them to 7726.
Can Self-Employed People Receive a P800?
No. The P800 is issued exclusively to individuals taxed through PAYE — employees and pensioners whose tax is deducted at source. Self-employed individuals, sole traders, and anyone with complex income sources do not receive a P800.
If you’re self-employed and believe you’ve overpaid tax, you claim any refund through your Self Assessment tax return. Once submitted, HMRC automatically calculates whether a repayment is due and will either transfer the refund directly to your bank account or offer to offset the overpayment against the following year’s tax bill.
Exception: If you receive both PAYE income and self-employment income, HMRC may still issue a P800 relating specifically to your PAYE earnings. Your self-employment tax position will be reconciled separately through Self Assessment.
I Haven’t Received a P800 — Can I Still Claim a Tax Refund?
Yes. Not receiving a P800 doesn’t mean you’re not owed a refund. HMRC only issues one when its systems detect a discrepancy — and those systems aren’t infallible. If you suspect you’ve overpaid tax in any of the past four years, you can:
- Log in to your HMRC Personal Tax Account and review your Income Tax summary
- Write directly to HMRC (marked ‘Repayment Claim’), enclosing your National Insurance number and supporting documentation such as P60s or P45s
You can also receive more than one P800 if HMRC conducts end-of-year reviews across multiple tax years simultaneously. Each letter covers a specific year independently, and any refund covering more than one year will typically arrive as a single combined payment.
Frequently Asked Questions: P800 Tax Refund
What is a P800 form in the UK? A P800 is a tax calculation letter sent by HMRC to PAYE employees and pensioners following the end of the tax year. It sets out whether you paid the correct amount of Income Tax, more than you owed, or less. If you overpaid, it explains how to claim a refund. If you underpaid, it outlines how HMRC plans to recover the shortfall — usually through an adjustment to your tax code.
How do I claim my P800 refund online? Visit gov.uk/p800refund and select ‘Claim now’. Sign in with your Government Gateway details. You’ll need the 10-digit reference number from the top of your P800, your National Insurance number, and your UK bank account details (sort code and account number). Refunds via this route are typically paid within 5 working days.
How long does a P800 refund take? Online claims through gov.uk or the HMRC app typically arrive within 5 working days. If HMRC is sending an automatic cheque (as stated in your letter), expect it within 14 days of the letter date. Requesting a cheque by phone can take up to 6 weeks.
What if my P800 shows I underpaid tax? HMRC will usually collect underpayments by adjusting your tax code for the next tax year, spreading the amount across 12 months. For underpayments above £3,000, or if you’d prefer to settle immediately, call HMRC on 0300 200 3300. A Time to Pay arrangement is also available if settling the amount upfront isn’t manageable.
What is the difference between a P800 and a P60? Your P60 is produced by your employer and records your total pay and the Income Tax deducted during the year. Your P800 is produced by HMRC and cross-checks those figures against its own calculation of what you should have paid. Think of the P800 as HMRC’s independent verification of your P60.
Can self-employed people get a P800? No. A P800 only applies to PAYE employees and pensioners. If you’re self-employed, your tax position is reconciled through Self Assessment, and any refund due is processed automatically after you submit your return.
How far back can I claim a P800 refund? You can claim overpaid tax for up to four complete tax years before the current one. As of 2026, that means claims can go back to 2021/22 — but the deadline for that year is 5 April 2026. Claims for 2022/23, 2023/24, and 2024/25 remain open with later deadlines.
What should I do if I think my P800 is incorrect? Compare the figures on your P800 against your P60, payslips, and any P11D forms from your employer. If something doesn’t add up, contact HMRC on 0300 200 3300 or submit a written challenge with your evidence. Don’t let an underpayment notice sit unaddressed — HMRC will proceed with tax code adjustments even without your input.
Is a P800 refund notification sent by text or email genuine? No. A genuine P800 will only arrive by post to your home address or appear in your HMRC Personal Tax Account online. HMRC does not send P800 refund notifications via text, email, WhatsApp, or social media. Any such message is a scam — forward suspicious emails to phishing@hmrc.gov.uk and report suspicious texts to 7726.
What happens if I don’t claim my P800 refund? Since 31 May 2024, HMRC no longer automatically sends cheques for most P800 refunds. If your letter says you can claim online, you must actively do so. Failing to claim doesn’t erase the refund from your tax record, but you will eventually hit the 4-year deadline — after which the right to that money expires permanently. Claim as soon as possible.