What Does the 1257L M1 Tax Code Mean?
Month 1 Emergency Code
description Core Meaning & Overview
The monthly variant of HMRC’s emergency non-cumulative coding, isolating deductions month-by-month.
account_balance Legal & Payroll Mechanics (2026/27)
Your employer gives you 1/12th of the annual Personal Allowance (£1,047.50) each month and taxes earnings above that in isolation. Year-to-date pay and tax totals are ignored on each monthly payslip.
warning Is Your 1257L M1 Tax Code Correct?
Check your HMRC Personal Tax Account at tax.service.gov.uk to ensure your previous employer reported your final leaving date and P45 details.
help Frequently Asked Questions About 1257L M1
What is the difference between 1257L and 1257L M1?
Standard 1257L is cumulative (considers total pay since 6 April). 1257L M1 is non-cumulative and treats every month as if it were Month 1 of the tax year.
How long does an M1 code stay active?
Usually 1 to 2 pay cycles until HMRC receives your P45 or starter declaration and sends an electronic P9 coding notice to your new employer.