A P800 is HMRC's end-of-year tax calculation letter. It tells PAYE employees and pensioners that, based on HMRC's records, they either paid too much or too little income tax during the year. If yours shows an overpayment, you can claim the refund online and get it by bank transfer within 5 working days, or do nothing and receive an automatic cheque within 14 days of the date on the letter. In summer 2026, HMRC is issuing around 4 million of these letters, mostly between June and August.
This guide explains who gets a P800, why overpayments happen, how to claim safely, how to tell a genuine letter from a scam, and what to do if yours says you actually underpaid.
What is a P800 and who gets one?
A P800 (sometimes called a "tax calculation") is how HMRC reconciles what you paid through PAYE against what you actually owed for the tax year. HMRC compares the tax deducted from your wages or pension with your correct liability, then writes to you if the two figures do not match.
You can get a P800 if you are:
- An employee taxed through PAYE.
- Someone receiving a workplace, private or state pension.
- Somebody whose circumstances changed mid-year (a new job, a second income, a benefit starting or stopping).
Importantly, if you are in Self Assessment, you will not get a P800. Your overpayment or underpayment is worked out and adjusted automatically through your tax return instead.
When are the 2026 P800 letters being sent?
HMRC issues P800 letters across a long window, from June through to March of the following tax year, once employers' and pension providers' year-end figures have been processed. The big refund batch lands earliest: this summer HMRC is sending roughly 4 million income tax refund letters, largely between June and August 2026. If you overpaid in 2025-26, your letter is most likely to arrive in this period.
Why do PAYE taxpayers overpay tax?
Overpayments almost always come from your tax code being wrong for part of the year, so the PAYE system deducts more than it should. Common triggers include:
- Being put on an emergency tax code (such as W1 or M1) or a BR code (all pay taxed at 20% with no tax-free allowance) after starting a new job.
- Starting or leaving a job part-way through the year, so your P45 details did not carry across in time.
- Having more than one job or pension, where the allowance gets split incorrectly.
- A company benefit (like a car or medical cover) changing or ending.
- Stopping work part-way through the year and not using your full personal allowance.
The standard code for 2026-27 is 1257L, reflecting the £12,570 tax-free personal allowance. If your payslip shows something different, such as BR or a code ending in W1/M1, that is often the root of an overpayment. Our guide to what tax code 1257L means breaks down how to read yours.
2026-27 figures and P800 refund timings at a glance
| Item | 2026-27 figure / rule |
|---|---|
| Personal allowance | £12,570 (frozen to April 2031) |
| Standard tax code | 1257L |
| Basic rate (20%) | £12,571 to £50,270 |
| Higher rate (40%) | £50,271 to £125,140 |
| Emergency / BR code effect | Pay taxed at 20% with no allowance |
| Refund by bank transfer (claimed online) | Within 5 working days |
| Automatic cheque (no online claim) | Within 14 days of the letter date |
| P800 letters sent (summer 2026) | Around 4 million |
A worked example: how a P800 refunds an emergency-code overpayment
Sana earns £30,000 a year (£2,500 a month). She changed jobs in August 2026 and her new employer put her on an emergency BR code for four months while her details caught up. Under BR, every pound is taxed at 20% with no personal allowance:
- BR tax each month: £2,500 × 20% = £500.
Her correct code (1257L) gives her £12,570 tax-free across the year, roughly £1,047.50 a month:
- Correct tax each month: (£2,500 − £1,047.50) × 20% = £290.50.
So for each of those four months she overpaid £500 − £290.50 = £209.50. Over four months that is £838 of tax she should never have paid. At the year end, HMRC totals her actual income (£30,000), applies her full £12,570 allowance, works out the tax genuinely due (£3,486), compares it with what was deducted, and issues a P800 refunding the roughly £838 difference. Claim online and it reaches her bank in 5 working days; do nothing and a cheque arrives within 14 days of the letter date.
You can sanity-check figures like these yourself with our income tax calculator before you claim.
How do you claim your P800 refund online?
If your P800 says you are owed money, the fastest route is to claim it yourself:
- Have your P800 reference number and your National Insurance number ready.
- Sign in to your Personal Tax Account or the free HMRC app.
- Choose HMRC's online bank transfer service to have the refund paid straight to your account, or request a cheque online.
Claim by bank transfer and the money arrives within 5 working days. For the full step-by-step, see our walkthrough on claiming an HMRC tax rebate on overpaid tax, and if an emergency code caused your overpayment, how to claim back emergency tax.
What if you do nothing?
You do not have to lift a finger. If you do not claim online, HMRC automatically sends a cheque, and you will receive it within 14 days of the date on your letter. Claiming online is simply faster.
How can you tell a genuine P800 from a scam?
This is where people lose money, so read it carefully. HMRC will never email, text, send a WhatsApp or other messaging-app message, or phone you to tell you about a tax rebate or refund. It will never ask for your bank details, personal information or a payment to "release" a refund through those channels. A genuine P800 refund is notified by post (a letter) or shows up in your Personal Tax Account, and that is it.
So any refund "notification" by email, text or call is a scam, full stop. To stay safe:
- Never click a link in a refund email or text. Instead, sign in directly to your Personal Tax Account at gov.uk to check.
- Forward a suspicious email to [email protected].
- Forward a suspicious text to 60599.
- Report a suspicious phone call through GOV.UK.
If you are ever unsure whether contact from "HMRC" is real, treat it as fake until you have confirmed it yourself inside your tax account. Worried about wider HMRC contact? Our explainers on whether HMRC can check your bank account and what triggers an HMRC investigation put genuine HMRC powers in context.
What if your P800 says you underpaid tax?
Not every P800 is good news. If HMRC's calculation shows you paid too little, there are two main outcomes:
- Coding out: HMRC usually collects a small underpayment by adjusting your tax code over the next year, so a bit more is taken from your wages or pension each month. You do not pay a lump sum.
- Simple Assessment: where the amount cannot be coded out (for example, you owe more than £3,000, or the tax cannot be taken automatically from your income), HMRC sends a Simple Assessment letter, such as a PA302, which you pay directly by the deadline on the letter.
Either way, do not ignore it. Check the figures against your own records first, because P800s are only as accurate as the data HMRC holds. Tracking what you have actually paid is easier with our guide to tracking tax payments to HMRC.
Should you double-check HMRC's calculation?
Yes. HMRC reconciles millions of records automatically, and mistakes happen when an employer or pension provider reports the wrong pay, or a benefit is recorded incorrectly. Compare the income and tax on your P800 with your final payslips, P45s and P60. If something looks off, contact HMRC (or ask an accountant) before accepting a refund or paying an underpayment, so you are not out of pocket either way.
Get a second pair of eyes on your P800
If your P800 is confusing, spans more than one job or pension, or you are not sure whether a refund is genuine, we can check it for you. Zmartly is a CIMA-regulated firm, and our qualified accountants (ACMA, CGMA, ACCA, FCCA) review PAYE calculations every week. Book a free call with Zmartly and we will tell you whether the figure is right and how to claim it safely.
Frequently asked questions
How long does a P800 tax refund take?
If you claim online by bank transfer using the reference on your P800 and your National Insurance number, the money reaches your account within 5 working days. If you do not claim online, HMRC sends a cheque automatically, which arrives within 14 days of the date on your letter.
Does HMRC email or text you about a tax refund?
No. HMRC never emails, texts, messages (including on WhatsApp) or phones you about a tax rebate or refund, and never asks for bank details or payment to release one. Genuine P800 refunds come by post or appear in your Personal Tax Account. Forward scam emails to [email protected] and scam texts to 60599.
Who gets a P800 from HMRC?
People taxed through PAYE (employees) and those receiving a pension get a P800 when HMRC's records show they paid too much or too little income tax for the year. People in Self Assessment do not receive one, because their bill is adjusted automatically through their tax return.
What happens if my P800 says I underpaid tax?
HMRC usually collects small underpayments by adjusting your tax code over the following year (coding out). Larger amounts, or those that cannot be coded out, come via a Simple Assessment letter (such as a PA302) that you pay directly by the deadline shown. Always check the figures against your payslips first.
