UK HMRC Forms Explained
Every UK HMRC form, reference number, and document you'll meet in the UK tax system — explained in plain English with practical guidance. P45, P60, P11D, NINO, UTR, SA100, plus the less-known forms (P85, P50, CWF1, P800) that matter when your circumstances change.
P45?
A P45 is the form your employer gives you when you leave a job. It records your earnings and tax paid in the current tax year up to your leaving date.…
P60?
A P60 is a year-end UK tax summary your employer must give you by 31 May after each tax year (which ends 5 April). It shows your total earnings, total…
P11D?
A P11D is a year-end UK form showing the cash value of any taxable benefits you receive on top of your salary — company car, private medical insurance…
National Insurance Number (NINO)?
Your National Insurance Number (NINO) is your unique UK tax and social security identifier — a 9-character code in the format AB123456C. It tracks you…
UTR Number?
A UTR (Unique Taxpayer Reference) is a 10-digit number HMRC assigns to anyone registered for self-assessment — sole traders, freelancers, landlords, c…
SA100 Self Assessment Form?
The SA100 is the main UK Self Assessment tax return form. It's the document that reports all your income, tax-deductible expenses, and tax paid to HMR…
P85? (Leaving the UK)
Form P85 is the UK form you complete when you're leaving the UK to live or work abroad permanently or for a long period. It tells HMRC you've left, so…
Starter Checklist (P46)?
The Starter Checklist (formerly P46) is the form you complete for a new UK employer when you don't have a P45 from your previous job. It captures basi…
P800?
A P800 is HMRC's annual tax calculation letter, sent if you've over- or under-paid tax during the year. If you owe HMRC, the P800 explains how much an…
CWF1 Form? (Self-Employed Registration)
Form CWF1 is the UK form for registering as self-employed with HMRC. It establishes your self-assessment record, generates your UTR, and starts your C…
P50? (Tax Refund When Stopping Work)
Form P50 is the UK form for claiming a tax refund when you've stopped working for at least 4 weeks and don't expect to work again in the current tax y…
Two reference numbers, three letter codes
Most UK taxpayers deal with two key reference numbers: NINO (National Insurance Number — for employment, NI, and State Pension) and UTR (Unique Taxpayer Reference — for self-assessment if you're self-employed or have other income). PAYE employees only need NINO; self-employed need both.
The three forms most UK employees see annually: P60 (year-end summary), P45 (when leaving a job), and P11D (if you have benefits-in-kind). The other forms only matter when circumstances change — leaving the UK, going self-employed, retiring, or HMRC reconciles your tax. Pair this guide with our UK tax codes explained for the full PAYE picture.