P45 Form is a form you get from your employer when you want to leave your company. A P45 shows how much tax you've paid on your salary so far in the tax year. Your employer should voluntarily give you a P45 when you leave the company. If your employer forgets to give, you should ask for the form since you're entitled to it by law. Our website provides you with several P45 Forms, such as Form P45 and P45 Form Download.