If your tax code has ‘W1’ or ‘M1’ or ‘X’ at the end these are "emergency tax codes". Tax codes with ‘K’ at the beginning mean you have income that is not being taxed another way ...

If your tax code ends with W1, M1 or X, you are paying emergency tax. For example: 1257L W1 – if you’re paid weekly. 1257L M1 – if you’re paid monthly. 1257L X – if you get paid irregularly.

She said: "Most people's tax codes are 1257L, this means you can earn up to £12,570 a year tax-free." M1 is a kind of ...

Workers across the country could claim thousands of pounds by keeping an eye out for a certain code on their payslips, HMRC says.