P45
A form your employer gives you when you leave a job, showing your tax code, total pay, and total tax paid in the current tax year up to your leaving date. You give Parts 2 and 3 to your new employer so they can set you up on the correct tax code from the start. Without a P45, your new employer may need to operate an emergency tax code until your details are confirmed.
How it works
Every employer is legally required to issue a P45 when you leave, and it exists to carry your tax history forward so you are not taxed incorrectly in your next job. It shows your tax code, total pay, and total tax paid up to your leaving date, which lets your new employer continue your PAYE record on a cumulative basis rather than starting from scratch.
If you do not hand over Parts 2 and 3 promptly, or you have no P45 at all, your new employer typically asks you to complete a starter checklist instead. This lets them apply a reasonable tax code, though it is often an emergency or non-cumulative code until HMRC confirms your correct position, which can mean you are over- or under-taxed for a short period.
A P45 is also useful outside employment changes. It can be needed as proof of income and tax paid when claiming certain benefits, and the figures on it feed directly into any Self Assessment return you complete for that tax year if you have income from multiple sources.
Frequently asked questions
What if I lose my P45?
Ask your former employer for a copy, or give your new employer a completed starter checklist instead so they can set your tax code correctly while HMRC reconciles the details in the background.
Do I need to give my new employer a P45 for a second job?
No, if it is not replacing your main job you generally don't hand over a P45; you complete a starter checklist marking it as a second job so the right code, often basic rate, gets applied instead.
What happens if my P45 arrives late?
Your new employer applies an emergency tax code in the meantime, which can mean you pay too much or too little tax for a pay period or two until your correct code and pay history are confirmed.
Related Terms
P60
An annual certificate your employer gives you at the end of the tax year (by 31 May) summarising your total pay and total tax deducted under PAYE for the year.
Tax Code
A code issued by HMRC to your employer to tell them how much income tax to deduct from your pay each period.
PAYE
Pay As You Earn — the system by which employers deduct income tax and National Insurance directly from employees' wages before paying them, and remit the deductions to HMRC on their behalf.