Type a tax code. It tells you the allowance it grants, the rate it applies, and whether it is an emergency code — for England, Wales and Scotland.
| Part | Meaning |
|---|---|
1257 | The number is your tax-free allowance with the last digit dropped. Multiply by 10: 1257 → £12,570 |
L | The standard Personal Allowance |
M | Marriage Allowance — you received 10% of your partner's allowance |
N | Marriage Allowance — you transferred 10% of yours to your partner |
T | Other calculations are included, or HMRC is reviewing an item in your code |
0T | No allowance at all. Often a new job with no P45, or an allowance already used up |
BR | Every pound taxed at basic rate. Normally a second job or a pension |
D0 / D1 | Every pound at higher / additional rate |
NT | No tax at all on this income |
K prefix | Deductions exceed your allowance, so the number is added to taxable pay rather than subtracted. Capped: it can never take more than half the payment |
S prefix | Scottish rates — six bands, not three |
C prefix | Welsh rates (Cymru). Currently identical to England's |
W1 M1 X | Emergency, non-cumulative. Each payslip is taxed in isolation, ignoring what you earned earlier in the year |
Scotland is not England with different numbers. An
S code runs against six bands — 19%, 20%, 21%, 42%, 45% and 48% —
where England has three. That is why SD0 means 21% while
D0 means 40%: the D-codes count bands above basic, and
Scotland has more of them. National Insurance is reserved and does not change.
Usually a benefit in kind (a company car, medical insurance), an underpayment being collected through the code, or expenses being allowed. Each adjusts the number up or down. HMRC sends a coding notice explaining it.
Not permanently. M1, W1 and X mean
each pay period is taxed on its own, so you often overpay at first. It corrects
once HMRC has a full picture, and anything overpaid comes back.
A K code adds to taxable pay instead of subtracting from it — but there is a 50% overriding limit, so no single payment can lose more than half to tax through the code. The rest is carried forward.
This decoder explains the code. To see what it does to an actual salary — your take-home, month by month, with the code applied — use the tax code checker on True Take-Home, which pairs the code with a wage. There are also written explainers for individual codes such as 1257L and BR.
Related: the income
tax calculator, the Scottish
income tax calculator for S codes, and the
payslip checker if the
figure on your payslip looks wrong.
The rates this page runs on are the open dataset at uk-tax-rates — free JSON, one file per tax year, fetched live from the CDN at page load.
No warranty. This explains published HMRC rules and is not tax advice. Your coding notice from HMRC is the authority on your own code.