Your P800 Explained
HMRC's end-of-year tax calculation letter, whether it says you're due a refund or that you owe tax
A P800 is the letter HMRC sends after the tax year ends if the tax taken from your pay through PAYE didn't match what you actually owed, either you're due a refund, or you owe some tax. It's sent between June and the following March, only to PAYE employees and pension recipients, not to anyone who files a Self Assessment return (their reconciliation happens through that return instead). Most people don't have to do more than check the figures and, if a refund's due, claim it.
The calculation, step by step
Click a box on the calculation below, or open any item in the list, to see what it means.
Tax calculation for the year
2026/27: Sam Taylor
Tax calculation for the year
Comparing what you paid
Illustrative example: you're due a refund.
Income
What it is: Your total taxable pay for the tax year from this job, plus any other employment or taxable benefits HMRC knows about.
Why it matters: This is the starting figure for the whole calculation, so it's worth checking first. Everything below is worked out from it.
What to check: Compare it against your P60 or your final payslip of the year. If it looks wrong, either too high, too low, or includes a job you didn't have, that's the first thing to query with HMRC.
Less your allowance
What it is: Your tax-free Personal Allowance for the year (£12,570 for most people) subtracted from your income to give your taxable income.
Why it matters: If this figure is lower than the standard allowance, something reduced it during the year. See Understanding Your Tax Code for what typically causes that.
What to check: Check it matches the allowance shown on your tax code for the year, unless you know of a specific reason it should be different.
Income Tax rate(s)
What it is: The tax due on your taxable income, worked out band by band. See Income Tax Explained for how the bands work. Sam's whole taxable income here falls in the basic rate band, so it's one figure at one rate; a higher earner would see this split across two or more rates.
Why it matters: This is what your tax bill would be with no complications before any adjustments are added.
What to check: Nothing to check directly here; it follows automatically once income and allowance are both correct.
Adjustments
What it is: Extra items added to or taken off your tax bill that the rate calculation above doesn't already cover. None applied to Sam this year.
Why it matters: This is the section HMRC's own research found most people struggled with, a bare '+£X other adjustments' with no explanation of what it actually is. Real P800s aren't always that clear about the source.
What to check: If you don't recognise an adjustment, or don't know why it's there, that's a reasonable thing to query with HMRC directly.
Result: tax due for the year
What it is: The rate calculation plus any adjustments. The total Income Tax HMRC has worked out you should have paid for the whole year.
Why it matters: This is the figure the letter compares against what was actually deducted from your pay, to work out your refund or bill.
What to check: This should equal the rate calculation above, plus or minus the adjustments line.
Tax already paid
What it is: What was actually deducted from Sam's pay through PAYE during the year. Here, more than they owed, because Sam started this job partway through the year and was briefly on an emergency tax code (see Emergency tax codes) before HMRC corrected it.
Why it matters: PAYE is designed to get this right automatically, but it works from the information HMRC and your employer had at the time, if that was incomplete or wrong for part of the year, this figure won't match what you actually owed.
What to check: Cross-check against the total tax figure on your P60 for the same year.
Refund due to you
What it is: Tax already paid, minus the tax actually due. The amount HMRC owes back to you.
Why it matters: You don't need to do anything to trigger this. See how refunds are actually paid out.
What to check: If this figure doesn't match your own rough calculation of the numbers above, that's worth querying with HMRC before acting on it.
Your tax history
What it is: A summary of any other tax years where HMRC sent you a P800. A year is only listed here if you were over- or underpaid; a year with no calculation sent means you paid the right amount and there's nothing to show.
Why it matters: HMRC's own research into this letter found this section was one of the most commonly misunderstood. Some real P800s show a running total that carries a balance forward from one year into the next, rather than every year being fully independent, which isn't obvious from the numbers alone.
What to check: If a past year here doesn't match what you remember happening (a refund you don't recall receiving, for instance), consider raising with HMRC directly rather than assuming it's correct.
If you are owed a refund
Your letter itself tells you which of two routes applies, so check the wording carefully rather than assuming:
- If it says you can claim online, use HMRC's online service (you'll need your P800 reference and National Insurance number) to have it paid straight into your bank account, which typically takes 5 working days, or to request a cheque instead.
- If it says HMRC will send a cheque automatically you don't need to do anything; it should arrive by post within 14 days of the date on the letter. If you're owed money from more than one tax year, it comes as a single combined cheque, not one per year.
If you owe tax
You can pay directly any time before the start of the next tax year (6 April). If you don't, HMRC collects it automatically by adjusting your tax code from 6 April onward, the same process covered in Understanding Your Tax Code, spreading the amount across your pay over the following year rather than taking it as a lump sum.
Is this the same as a Simple Assessment?
No, a similar-sounding but separate letter. HMRC sends a Simple Assessment instead of a P800 when the amount owed is £3,000 or more, or when tax is due on income (like State Pension) that can't be collected through a tax code at all. A Simple Assessment has its own fixed payment deadline (31 January following the tax year, or three months from the letter if it arrives after 31 October) rather than the automatic tax-code adjustment a P800 uses. If your letter is headed "Simple Assessment" rather than "P800" or "tax calculation," the rules on this page don't apply to it.
Watch out for tax refund scams
Tax refunds are one of the most common scam themes used to impersonate HMRC. A P800 itself always arrives by post, never by text or email, so treat any text or email claiming you're owed a refund and asking you to click a link or enter bank details as fraudulent. HMRC's own guidance is explicit: a genuine refund text will never ask for personal or financial information and will never contain a link. If you're not sure, don't click anything. Check directly via your personal tax account, the HMRC app, or a phone number you've looked up independently, not one given in the message itself.
This page explains what a P800 shows and is not personalised advice; see the disclaimer. Always refer to your own letter as the source of truth for your figures.