Thetax code 1257L is used in the calculation of PAYE (Pay As You Earn) income tax by employers. It enables workers to receive up to 12570 pound per year income tax free. Income supplementary to this amount is liable to tax as per the normal UK tax bands. This code is applicable in a case where there are no other sources of income and allowable deductions. Your code can be adjusted by HMRC when you: change jobs or claim benefits. Look at your payslip and make sure that you have the right code so that you do not end up underpaying or overpaying tax.