You will get a P45 when you stop working for an employer and you need to give this to a new employer.

The P45 shows how much money you have earnt in the current tax year (6 April to 5 April)and what tax you have paid.

It will show the code that the Tax office has used to calculate your tax and whether they have you on a cumulative or week 1 tax code. The new employer is required to send this to the Tax Office who issue a code detailing how much tax they have calculated you need to pay.

If you don’t have a P45 you will be asked to complete a Starter Checklist (previously called P46).

The Starter Checklist has questions about any other jobs, benefits or student loans you have. It helps your employer work out your correct tax code before your first payday.

How long is a P45 valid for?
A P45 is only valid throughout the tax year in which it was provided, but that doesn’t mean you should shred it straight after. You should keep it on record for at least 22 months after the end of the relevant tax year. However, you may wish to retain it for longer, as HMRC has the right to carry out tax investigations up to 20 years after the point.