A P45 is a certificate given by an employer to an employee at the end of their employment. It includes details of their tax code, gross pay and the amount of tax they’ve paid so far that year.
When you receive a P45, give parts 2 and 3 to your new employer or benefit agency. This helps ensure you pay the correct amount of tax.
It’s a good idea to keep part 1A somewhere safe, as you may need it if you ever have to prove your income. For example, if you’re applying for tax credits or completing a Tax Return.