A P45 is the record of what you earned and paid in tax before you left a job. What is on it, what to do with each part, and how to fix it when it is wrong.
Nobody thinks about a P45 until the week they need it, which is usually the week they have already thrown it away. It arrives with a final payslip, looks like admin, and gets filed in the same drawer as the takeaway menus.
It is worth more attention than that. Handing the right parts of it to the right people is often the difference between a correct first payslip in a new job and three months of quietly overpaying tax.
It is the legal record of how much you were paid and how much income tax you paid in the current tax year, up to the day you stopped working for that employer.
That is all it does. It is not a reference, it is not proof of employment history, and it says nothing about why you left.
Five things matter, and they are the five your next employer’s payroll will type in.
Note what is missing. There is no National Insurance figure, because NI is worked out fresh each pay period and never carries over. There is no pension detail. And there is no record of pay from any other job you held in the same year.
The form comes in parts, and the split confuses almost everyone.
The single most common mistake is handing over Part 1A and keeping Parts 2 and 3, which leaves you with nothing for your records and your new employer with a document they cannot process. The gov.uk summary of P45, P60 and P11D forms sets out the split if you want it in writing.
Say you earn £30,000, so £2,500 a month on tax code 1257L, and you leave on 31 August 2026. That is the end of month 5 of the 2026/27 tax year.
Your P45 should show:
1257LNow you take September off and start a new job at the same salary in October, which is month 7.
With the P45 handed over. Payroll continues cumulatively. Your year to date pay becomes £15,000 and your allowance to month 7 is 7 ÷ 12 × £12,570 = £7,332.50, so taxable pay to date is £7,667.50 and tax due for the year so far is £1,533.50. You have already paid £1,452.50, so your October tax is just £81.
Without it. Your new employer puts you on 1257L week 1 or month 1 from a starter checklist. Payroll ignores your year to date position and charges £2,500 minus £1,047.50 at 20 per cent, which is £290.50.
That is £209.50 of tax in one month that you did not need to pay, and it is exactly one month’s personal allowance at basic rate. It happens because the unpaid September went unused. The P45 is what tells payroll to give it to you.
Employers must issue a P45 to anyone leaving PAYE employment. There is no fixed statutory deadline, but the expectation is without unreasonable delay, and in practice it comes with or shortly after your final payslip.
If a month goes by, email payroll directly. Something like this works:
I left on [date] and have not yet received my P45. Please confirm when it will be issued, or send a statement of earnings showing my total pay and tax for 2026/27 up to my leaving date. My National Insurance number is [number].
If the employer has gone into administration or simply will not respond, you have two fallbacks. Your Personal Tax Account shows the pay and tax your employer reported to HMRC in real time, which gives you the figures even without the paperwork. And your new employer can put you on a starter checklist instead, which keeps you paid while HMRC catches up.
One thing that does not work: asking HMRC for a copy. They do not issue duplicate P45s, and neither is your old employer obliged to print a second one.
If you have no P45, your new employer will ask you to tick one of three statements. Pick carefully, because it sets your code.
1257L on a cumulative basis, which is the best outcome.1257L on a week 1 or month 1 basis, so no year to date link and probably a temporary overpayment.BR, which taxes every pound at 20 per cent with no allowance.People who left a job months ago often tick B when A is closer to the truth, or tick C by mistake because they have a small pension. Both cost money until HMRC corrects the code.
0T, and it will not appear on the P45.All four are fixed by the old employer’s payroll, not HMRC.
The form itself has not changed. What has changed over recent years is that Part 1 is essentially a formality: employers report your leaving pay and tax to HMRC through Real Time Information as part of the normal payroll submission, so HMRC usually knows you have left before the paper reaches them.
The practical consequence is that your Personal Tax Account is now a reliable substitute for a lost P45 in a way it was not a decade ago. HMRC’s move to digital-first P2 code notices in April 2026 pushes the same way: if your new employer gets your code wrong, the correction now appears online rather than in the post, so check the app rather than waiting for a letter.
BR.If you want to check that your first payslip in a new job actually used the figures on your P45, the NetPay app works out what your take-home should be from your code, your pay, and your year to date position. Free to download.
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A P45 is the record your employer gives you when you leave a job, showing your pay and tax for the current tax year up to your leaving date. Your next employer uses it to continue taxing you cumulatively rather than starting from scratch, which is what stops you overpaying tax in your first few months.
No. HMRC does not issue duplicate P45s and your old employer is not required to produce a second one. Instead ask them for a statement of earnings on headed paper, or check your pay and tax figures in your Personal Tax Account, then complete a starter checklist for your new employer.
A P45 covers a part year and is issued when you leave a job. A P60 covers a full tax year and is issued by your current employer by 31 May each year for everyone still employed on 5 April. You can have several P45s in a tax year but only one P60 per employer.
Yes. Employers must give a P45 to anyone leaving PAYE employment, regardless of how long they worked or how little they earned. If you earned below the tax threshold the form will show zero tax, but the pay figure still matters because it keeps your next employer's cumulative calculation accurate.
Want to see your actual take-home pay?
NetPay UK works out your real net pay after tax, NI, pension and salary sacrifice, for hourly, shift and variable-income workers. Free to download.
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A note on financial advice: NetPay UK calculates take-home pay based on official HMRC tax rules. This article reflects rules in force at the time of publication (20 August 2026). Tax rules change. For complex situations, consult a qualified UK accountant or visit gov.uk/income-tax.
