The P45 explained
When you stop working for an employer, they will provide you with a P45 form. This form is to show how much tax you’ve paid on your salary so far in the tax year. A P45 has four parts: Part 1 is sent to HMRC, part 1A is for your records and parts 2 and 3 are to give to a future employer or to JobCentre Plus if you’re unemployed. By law, you must be provided with a P45 so be sure to ask for one.
The P60 explained
The P60 form shows what you have earned and also the tax you’ve paid on your salary, if you are working at the end of the tax year. P60 forms can be useful as they can be used to check whether you have overpaid on tax. HMRC provide a useful tool to calculate whether you’re due a rebate.
The P11D explained
The P11D form will be sent directly to HMRC by your employer if you’re provided with any ‘benefits in kind’ including company cars or interest-free loans. The P11D records how much each benefit is worth and will be sent to HMRC if your earnings including company benefits are greater than £8,500 in the tax year. Your employer will usually provide you with a copy, but if they don’t, by law they must at least inform you of its contents.