What is a P45 ?

P45 is a tax document the employer provides to employees when they stop working. It contains the salary and taxes paid to date in the tax year. 

At the start of a job, one may have to give the P45 to the employer, which shows they can deduct the right amount of tax from the salary. 

Without this form, one may be on an emergency tax basis. By law, you should ask the employer to get the contract P45 explained, where the employer sends details of part 1 to the HMRC, and Parts 2 and 3 are given to the new employer.