Tax code calculators
What does my tax code mean?
Read your code from left to right: where you pay tax, how much is tax-free, why, and whether each pay stands alone.
Tax-free pay from this job
£11,000 a year
- 1100 × 10 = £11,000, and the letter L means the standard tax-free Personal Allowance.
- Scottish rates
- Emergency basis (M1): each pay is taxed on its own, as if it were the first of the year
| Tax-free pay each month | £917.43 |
| Tax over the year on £28,000 | £3,356.52 |
| That is, each month | £279.71 |
| With S1257L instead | £3,044.33 |
Estimate with HMRC’s payroll method and the same pay every month. Only HMRC can change your code.
Every UK tax code can be read in four pieces from left to right, and each piece answers one question. An S or C at the start says your income is taxed at the Scottish or Welsh rates; no prefix means the rates for England and Northern Ireland. The number is your tax-free pay from this job with the last digit removed, so 1100 means £11,000. The letter after it says why the allowance has that size: L for the standard one, M or N for Marriage Allowance received or given, T when other calculations are part of it. A code may instead be two letters with no number, such as BR or NT, which replace the allowance altogether, or start with K, which adds to pay. Finally, W1, M1 or X means each pay is taxed on its own. S1100L M1 on £28,000 a year therefore means Scottish rates, £11,000 tax-free, a benefit or deduction already taken off, emergency basis: £3,356.52 over the year.
Tax-free pay behind a code number
Tax-free a year
£11,000
| Free pay in month 1 | £917.43 |
| Free pay in week 1 | £211.73 |
| Against the Personal Allowance | −£1,570 |
HMRC’s tables add £9 to the code number × 10, so the free pay is a few pence above a twelfth of it.
Rules read on HMRC’s texts by Radif Partners · Editorial policy · Method
Twelve codes decoded
The table applies each code to the same £30,000 a year paid monthly, so you can see how much the prefix, the number and the letters matter. Figures follow HMRC's payroll method for 2026 to 2027 (PAYE specification).
| Code | What it says | Tax-free a year | Tax on £30,000 |
|---|---|---|---|
| 1257L | Standard allowance | £12,570 | £3,484.00 |
| 1383M | Marriage Allowance received | £13,830 | £3,232.00 |
| 1131N | Marriage Allowance given | £11,310 | £3,736.00 |
| 1100T | Other calculations | £11,000 | £3,798.00 |
| S1257L | Scottish rates | £12,570 | £3,448.97 |
| C1257L | Welsh rates | £12,570 | £3,484.00 |
| K475 | Amount added to pay | −£4,750 | £6,951.80 |
| BR | All at basic rate | £0 | £6,000.00 |
| D0 | All at higher rate | £0 | £12,000.00 |
| 0T | No allowance, normal bands | £0 | £6,000.00 |
| NT | No tax | £0 | £0.00 |
| 1257L M1 | Emergency basis | £12,570 | £3,482.40 |
The prefix: where you pay tax
HMRC decides whether you are a Scottish or Welsh taxpayer from where you live, and the prefix tells payroll which rates to use. S sends the pay through the six Scottish bands, from 19% to 48%. C applies the Welsh rates, which give the same totals as England in 2026 to 2027. A missing prefix when you live in Scotland, or an S when you have moved to England, is a common error worth checking in your HMRC online account. The emergency code has no prefix: it is the same across the UK.
Scottish rates against England
Tax with S1257L
£3,448.97
| With 1257L (England) | £3,484.00 |
| Difference over the year | −£35.03 |
| Each month | −£2.92 |
The number and the letter
The number times ten is the yearly tax-free pay from this job. Payroll converts it with HMRC's tables, which add £9 before dividing, so 1257 gives £1,048.26 a month rather than an exact twelfth. The letter after the number is a label: L for the standard allowance, M when your partner has transferred Marriage Allowance to you, N when you have transferred it, T when your allowance includes other calculations HMRC has made. Some codes have no number at all: BR, D0, D1, 0T and NT. A K code has a number that is added to pay.
Where your code is printed
The code appears on every payslip, usually near your National Insurance number, and on your P60 at the end of the tax year. HMRC's online service and app show the code for each job and pension, with the calculation behind it and the codes of earlier years (GOV.UK tax codes). When HMRC changes a code it may also send a coding notice listing each allowance and deduction. If two documents show different codes for the same job, the most recent one from HMRC is the one your employer should be using; a payslip can lag a new code by one or two pay days.
The end of the code: cumulative or not
Without anything after the letter, the code is cumulative: each payslip looks at the whole year so far. W1 (weekly pay), M1 (monthly pay) and X (irregular pay dates) switch to the emergency basis described on GOV.UK, where each pay is taxed alone. The W1, M1 and X page explains when this costs you money and how it is reversed.