Along with your payslips, your umbrella employer is obliged to provide you with a P60 each year.
A P60 is a form that explains how much you’ve earned over the tax year (which runs from 6 April to 5 April the following year). It also includes how much you’ve paid in National Insurance contributions and Pay As You Earn (PAYE) income tax. As well as your regular payslips, your umbrella employer must provide you with a P60 by 31st May, following the relevant tax year.