Tax codes explained

HMRC sends your employer or pension provider a short code that tells payroll how much tax-free pay to give you and which rates to charge on the rest. The most common one for 2026/27 is 1257L, the standard £12,570 Personal Allowance, applied to that one job. Your code is printed on your payslip and in your HMRC personal tax account.

What the number means

The digits are your tax-free allowance for that job with the last digit removed. Multiply by ten to get the rough amount:

• 1257L means £12,570 tax-free.
• 1157L means about £11,570 tax-free, perhaps because HMRC has taken off £1,000 for a taxable benefit or for tax you owe from an earlier year.
• 1383M means about £13,830, which is the standard allowance plus £1,260 of Marriage Allowance received from a partner.

Anything below 1257 means less tax-free pay and more tax, and anything above means the opposite. HMRC lists every adjustment in your personal tax account and in the coding notice it sends you, usually under “allowances” and “deductions”.

What the letters mean

The letter at the end, and some codes with no number at all, tell payroll how to treat you.

Code	What it means
L	Standard tax-free Personal Allowance
M	You have received Marriage Allowance from your partner
N	You have transferred Marriage Allowance to your partner
T	Other calculations were needed to work out your allowance
0T	No tax-free allowance from this job
BR	All pay from this job taxed at the basic rate (20%)
D0	All pay from this job taxed at the higher rate (40%)
D1	All pay from this job taxed at the additional rate (45%)
NT	No tax taken from this income
K (before a number)	Untaxed income or benefits exceed your allowance, so an amount is added to taxable pay

BR, D0 and D1 usually appear on a second job, where your main job already uses the allowance. The BR tax code guide covers when that goes wrong. K codes are rarer and have their own guide, K tax codes.

S and C prefixes

An S at the front means you are a Scottish taxpayer and payroll should use Scottish rates on your wages: S1257L, S0T, SBR and so on. Scottish codes also include SD0, SD1, SD2 and SD3, which tax all income from that job at the intermediate, higher, advanced and top rates.

A C means Welsh rates: C1257L, C0T, CBR, CD0 and CD1. For 2026/27 these give the same result as the English rates.

The prefix follows your main home, not your employer’s location. A nurse who lives in Dumfries and works in Carlisle should have an S code. A wrong prefix means telling HMRC your correct address. See Scottish S tax codes and rates and Welsh C tax codes.

W1, M1 and X suffixes

These mark an emergency basis. Normal PAYE is cumulative, so each payday it looks at everything you have earned and paid since 6 April. A code ending W1 (week 1), M1 (month 1) or X is non-cumulative, and tax is worked out only on that week’s or month’s pay. The 2026/27 emergency codes are 1257L W1, 1257L M1 and 1257L X.

On a non-cumulative code you still get one twelfth (or one fifty-second) of your allowance each period, but nothing for the months you missed. Start a job in October after months without work and you can overpay until the code is corrected. Emergency tax codes explains how to get it changed.

Why your code changes during the year

HMRC can issue a new code at any point. Common triggers in public sector jobs:

• starting a second job, such as NHS bank shifts alongside a substantive post
• a benefit in kind starting or stopping, such as a lease car through salary sacrifice in some schemes
• claiming a flat-rate expense for uniform or a deduction for professional fees, which raises the allowance
• underpaid tax from an earlier year being collected through this year’s code
• moving between Scotland and the rest of the UK
• income passing £100,000, which starts to reduce the allowance.

Your employer receives the new code electronically and must use it from the next payday. A code that arrives late in the year is caught up by the cumulative system, which can mean a refund or a larger deduction in one month.

Checking your code

Sign in to your HMRC personal tax account or the HMRC app. It lists each employer and pension, the code each is using, and how HMRC worked it out. Compare the income figures with what you actually earn, because HMRC sometimes estimates a bank or overtime-heavy job too high and leaves the main job with too little allowance. How to check your tax code goes through the screens.

To correct a code, update your estimated income in the personal tax account or call HMRC. Payroll staff cannot change it themselves, though they can tell you which code they have on file and when it arrived. Overpaid tax normally comes back through your pay once the code is fixed within the same tax year. For earlier years, HMRC reconciles your record after the tax year ends.