Tax codes one by one
Tax code letters
Where a letter sits tells you what it does: after the number, in front of it, instead of it, or at the very end.
Tax-free pay from this job
£13,830 a year
- 1383 × 10 = £13,830, and the letter M means Marriage Allowance received: 10% of your partner’s Personal Allowance is added.
- Scottish rates
- Cumulative: allowance and bands build up through the tax year, so over- or under-payments correct themselves
| Tax-free pay each month | £1,153.26 |
| Tax over the year on £32,000 | £3,604.37 |
| That is, each month | £300.36 |
| With S1257L instead | £3,868.97 |
Estimate with HMRC’s payroll method and the same pay every month. Only HMRC can change your code.
The letters in a tax code fall into four groups, and their position tells you which group you are looking at. A letter after the number, such as L, M, N or T, describes your situation but does not change the arithmetic: 1257L, 1257M or 1257T all give £1,048.26 of free pay a month. A letter in front changes how the code works: K adds the number to your pay instead of giving it tax-free, S applies the Scottish rates and C the Welsh rates. Some codes are letters only: BR charges 20% on everything, D0 40%, D1 45%, 0T gives no allowance but keeps the bands, and NT takes no tax at all. Finally, W1, M1, X or NONCUM at the end switch the code to a week 1 or month 1 basis, where each pay is taxed alone. The comparison shows how much the letter matters: on £30,000 a year, 2026 to 2027 rates give £3,484.00 with 1257L, £6,000.00 with 0T, £6,000.00 with BR and £12,000.00 with D0. Each letter below links to its own page.
Two codes on the same pay
0T against 1257L, over the year
+£2,516.00
| Tax with 1257L | £3,484.00 |
| Tax with 0T | £6,000.00 |
| Each month | £209.67 |
Rules read on HMRC’s texts by Radif Partners · Editorial policy · Method
Every letter in one table
The table brings together the letters listed by GOV.UK for employees and by the employer guidance for payroll staff, sorted by where they appear in the code. Rates are those of 2026 to 2027 for England and Northern Ireland.
| Letter | Where it sits | What it does |
|---|---|---|
| L | After the number | Standard Personal Allowance |
| M | After the number | Marriage Allowance received, £1,260 added |
| N | After the number | Marriage Allowance transferred, £1,260 taken off |
| T | After the number | Allowance includes other calculations HMRC reviews |
| K | In front of the number | Deductions exceed the allowance: number × 10 added to pay, tax capped at 50% of pay |
| S | In front | Scottish rates and bands |
| C | In front | Welsh rates |
| BR | Whole code | All pay at the basic rate, 20% |
| D0 | Whole code | All pay at the higher rate, 40% |
| D1 | Whole code | All pay at the additional rate, 45% |
| 0T | Whole code | No allowance, normal bands from the first pound |
| NT | Whole code | No tax deducted; no Scottish or Welsh version |
| W1 | Ending | Week 1 basis for weekly pay |
| M1 | Ending | Month 1 basis for monthly pay |
| X | Ending | Non-cumulative basis when pay dates vary |
| NONCUM | Ending | Printed by some payroll software for the same basis |
The same pay under different letters
Here the pay stays fixed and only the code changes: £2,500 in one month and £30,000 over a year. The first four lines show that suffix letters do nothing on their own; the difference between 1383M and 1131N comes from their numbers. The flat codes and 0T show what losing the allowance costs, and the S line shows the effect of the Scottish bands at this level of pay.
| Code | Tax in month 1 on £2,500 | Tax over the year on £30,000 |
|---|---|---|
| 1257L | £290.20 | £3,484.00 |
| 1383M | £269.20 | £3,232.00 |
| 1131N | £311.20 | £3,736.00 |
| 1257T | £290.20 | £3,484.00 |
| 0T | £500.00 | £6,000.00 |
| BR | £500.00 | £6,000.00 |
| D0 | £1,000.00 | £12,000.00 |
| S1257L | £287.27 | £3,448.97 |
| C1257L | £290.20 | £3,484.00 |
Tax each month with a code
Tax in month 1 with 1257L
£290.20
| Tax over 12 months | £3,484.00 |
| Average each month | £290.33 |
| With 1257L instead | £3,484.00 |
How to read a full code
Take the code from left to right. A prefix comes first: S or C for the nation, or K when the number is added to pay. A Scottish K code reads SK, a Welsh one CK. Next comes the number, the tax-free amount divided by ten, explained on the page on code numbers. Then the suffix letter. Last, after a space, any ending that changes the basis. So S1257L M1 means Scottish rates, £12,570 tax-free, standard allowance, month 1 basis.
A few combinations never appear. HMRC's PAYE specification rules out SNT and CNT, and it gives the emergency code no S or C prefix because a single emergency code serves the whole UK. Outside Scotland there is no D2, since the scale stops at the additional rate; in Scotland the flat codes run from SBR to SD3, listed on the Scottish codes page.
Endings and why they matter
GOV.UK treats a code ending in W1, M1, X or NONCUM as an emergency code. The ending does not change the allowance; it stops the running total, so allowance not used in earlier weeks or months is not given back. A code with no ending is cumulative, which is the normal state. If your code has carried an ending for weeks, or a letter in the table does not match your situation, check your record in your HMRC online account.