P800 Tax Calucation: Claim Your Tax Refund with HMRC

With millions of PAYE records being reviewed in 2026, many taxpayers are receiving P800 letters. This guide explains why you received one, how to check the calculation, claim any refund, deal with tax owed and avoid HMRC scams.

A P800 is a PAYE tax calculation, not a Self-Assessment return or Simple Assessment bill. HMRC usually sends P800s between June and March of the following tax year. The letter will tell you whether you are due a refund or owe more tax and explain what happens next. If HMRC has reviewed several tax years together, use the latest P800 and its tax history to understand your overall position.

Other changes can also affect your final tax position, including:

• starting a job on an emergency tax code
• having more than one job or pension
• stopping work part-way through the tax year
• changes to savings interest or taxable employment benefits
• taking a flexible pension payment taxed using an emergency code
• changes to Marriage Allowance
• corrections to pay or tax information reported by your employer

Scam Checklist:

•  Did you receive a P800 letter by post first?
• Does the text or email ask you to click a link to claim, release or verify your refund? A genuine P800 follow-up message will not.
• Are you being asked for bank details, card numbers or personal information? Treat the message with caution.
• Are you being pressured to act within 24 or 48 hours? Unexpected urgency is a common warning sign.
• Can you confirm the refund independently through the HMRC app, your Personal Tax Account or GOV.UK?
• Is anyone asking for your Government Gateway or GOV.UK One Login details? Never share your HMRC sign-in details, even with a tax agent.

A tax refund agent is a private company, not HMRC. Some offer a useful service, but others take a sizeable fee from a refund you could often claim yourself for free. Before signing up, check what they charge, whether the fee covers one tax year or several, and whether the refund will be paid to you directly or to the agent first.

If you previously signed a deed of assignment giving a refund company the right to receive your repayment, the rules have changed. Under section 333 of the Finance (No. 2) Act 2023, any assignment received by HMRC on or after 15 March 2023 is void, even if you signed it before that date. A nomination is different and can still allow HMRC to pay a refund to someone else on your behalf. For most P800 refunds, you do not need an agent — you can usually claim directly from HMRC and keep the full amount.

Your P60 and P800 will not always agree. A P60 is your employer's year-end certificate, and where you handed over a P45 it should already cover your whole year across both jobs. So a P60 that only shows part of the year is itself a clue: your new employer never processed your P45.

The other common cause is income a P60 was never meant to show — pension income, savings interest, or benefits on a P11D. HMRC builds your P800 from all of it, which makes it more complete than your P60, but not automatically right.

Worked Example: Mid-Year Job Changes with No P45

Scenario: Priya earns £2,500 a month. She works from April to September 2025, has no earnings for three months, then starts a new job in January 2026 without a P45. She completes Starter Checklist Statement B, so her new employer uses the 1257L Month 1 emergency tax code.

Tax Deducted

Job A:

£15,000 pay − £6,285 allowance = £8,715 taxable
£8,715 × 20% = £1,743 tax

Job B:

£2,500 − £1,048 monthly threshold = £1,452 taxable per month
£1,452 × 20% = £290.40 tax per month
£290.40 × 3 = £871.20 tax

What should Priya actually pay?

£22,500 − £12,570 Personal Allowance = £9,930 taxable

£9,930 × 20% = £1,986 tax due

But Priya paid £2,614.20

£2,614.20 − £1,986 = £628.20 overpaid

Result: Priya is due a £628.20 refund

The overpayment arose because the Month 1 emergency code taxed each month separately and did not take account of the allowance Priya had not used during her three months without work. HMRC can identify this when it reviews her full-year PAYE record.

Most landlords will not receive a P800. If your only income is from property, your tax will usually be dealt with through Self-Assessment or, in some cases, Simple Assessment. A P800 is more likely where you also have income taxed through PAYE, such as a salary or pension, and HMRC is reconciling your tax without a Self-Assessment return for that year.

If your P800 includes property income, check the figure carefully. HMRC may be using an estimated amount based on information from an earlier year rather than your actual current profit. If your rent has fallen, a property has been sold or you have had a long vacant period, that estimate could be too high and you may end up paying more tax than necessary.

You also do not need to wait for a P800 to correct an inaccurate estimate. Check your tax code through your Personal Tax Account or the HMRC app and contact HMRC if the property figure needs changing. Remember, you could still receive a P800 for an earlier tax year even if you have since registered for Self-Assessment.

If your P800 says you can claim online, you need to take action to get your refund. Do not assume HMRC will automatically send a cheque. You will usually need the reference number from your P800 and your National Insurance number.

You can claim in several ways:

• Claim online through GOV.UK and choose payment into your bank account or by cheque
• Use the HMRC app. Go to the PAYE section and select Claim if a refund is available. You will need a UK bank account
• Use your Personal Tax Account to request payment into your UK bank account
• Contact HMRC if you prefer to receive your refund by cheque

HMRC says online refunds are normally sent within 5 working days, while a cheque you request can take up to 6 weeks.

If your P800 specifically says HMRC will send you a cheque, you do not need to make a claim. It should arrive within 14 days of the date on the letter. If you are due refunds for more than one tax year, HMRC will normally send one cheque for the total amount.

Before claiming, check that the figures on your P800 are correct. If something does not look right, contact HMRC before accepting the calculation.

Sometimes HMRC cannot use your tax code at all. That happens if you owe more than £3,000, if your income is too low to absorb the deduction, or if the tax is due on your State Pension. In those cases, you get a Simple Assessment letter rather than a P800. Treat it as a different document entirely: it carries a payment deadline and missing that deadline costs you interest. If your tax is being coded out and you would rather clear it now than watch it come out of every payslip for a year, you can pay it early.

If you think the figures are wrong, contact HMRC before paying. Explain which amounts you believe are incorrect and what the correct figures should be. Keep documents such as your P60, P45 and payslips available to support your position.

If a refund or underpayment looks unusually large, check it carefully. HMRC can recover money that was refunded in error, so it is better to query an unexpected figure than assume the calculation must be right.

Before making a claim, check your records for other recent tax years as well. You may find that another refund is due, or that a different year contains an underpayment that also needs correcting.

You also do not need to wait for a P800 if you think you have paid too much tax. Depending on the reason for the overpayment:

• P50 – May apply if you have stopped working and want to claim back overpaid Income Tax.
• P87 – May apply if you have paid qualifying work expenses yourself and want to claim tax relief.
• P85 – May apply if you have left or are leaving the UK and are not reporting your departure through Self-Assessment.

HMRC’s Check how to claim a tax refund service can help you find the right route for your situation.

If you receive an HMRC P800 tax refund letter, check the figures before you claim or pay anything. Make sure the income, tax and any property-related amounts are correct, then take action through GOV.UK, the HMRC app or your Personal Tax Account.