UK Tax Codes Explained (2026/27): 1257L, BR, K, 0T & W1/M1

Your tax code is the short string — usually something like 1257L — that tells your employer's payroll software how much income tax to take off each payslip. It is not random: every character means something specific, and once you can read it you can tell at a glance whether you're being taxed correctly. This guide decodes every part for the 2026/27 tax year.

The two halves of a tax code: a number and a letter

Almost every code splits into a number and a letter (sometimes with a prefix or suffix). The number sets your tax-free amount; the letter sets the rule that applies to it.

• The number is your annual tax-free Personal Allowance with the final digit dropped. Multiply it by 10 to get the cash figure: 1257 → £12,570. That's the slice of your pay each year that carries no income tax.
• The letter tells payroll which rule to apply — whether you get the full allowance, a reduced one, none at all, or a flat rate on everything.

1257L — the standard 2026/27 code

If you have one job, no taxable perks and no untaxed income, your code is 1257L. It gives you the full £12,570 Personal Allowance, after which your pay is taxed at 20% up to £50,270, 40% up to £125,140, and 45% above that. The L simply means "standard allowance". This is the baseline every figure on our Salary Calculator and salary tables assumes unless you tell it otherwise.

The suffix letters: L, M, N and T

• L — the standard Personal Allowance (£12,570).
• M (Marriage Allowance, receiver) — you've received 10% of your spouse's allowance, so your tax-free amount is raised by about £1,257. The code becomes something like 1383M.
• N (Marriage Allowance, giver) — you've transferred 10% of your allowance to your partner, so your tax-free amount is reduced. Code looks like 1131N.
• T — your code includes other calculations HMRC reviews individually (common above £100,000, where the allowance is being tapered). It behaves like an allowance code but flags a non-standard figure.

0T — no allowance, but still banded

0T ("zero-T") gives you no Personal Allowance: you're taxed from the very first pound. Crucially, it still steps through the normal 20% / 40% / 45% bands as your pay rises — that's what separates it from BR below. You'll see 0T as an emergency code when a new employer has no P45 or starter-checklist details, and permanently once income above £125,140 has tapered the allowance away entirely (the £100k tax trap).

BR, D0 and D1 — flat-rate codes

These apply a single flat rate to all the income under the code, with no allowance — they're used on second jobs and pensions where your allowance is already spent elsewhere.

• BR — Basic Rate, a flat 20% on everything.
• D0 — a flat 40% (Higher Rate) on everything.
• D1 — a flat 45% (Additional Rate) on everything.

BR on a second job is usually correct — your first job is using your allowance. BR on your main job is a red flag that your allowance hasn't been assigned to the right employer yet.

K codes — when deductions exceed your allowance

A K code is the mirror image of a normal code. When your taxable perks or untaxed income (a company car, medical insurance, the State Pension, or unpaid tax from a previous year) are larger than your tax-free allowance, the surplus is added to your taxable pay instead of subtracted from it — a "negative allowance". To stop a K code swallowing a whole payslip, HMRC limits the tax it can take to 50% of your gross pay in any single pay period; our calculator applies that same 50% cap and flags when it has kicked in.

NT and the W1 / M1 emergency marker

• NT — No Tax. Rare, and only used in specific cases (for example certain non-residents or specific pension arrangements).
• W1 / M1 — "week 1 / month 1". This is a non-cumulative emergency marker: payroll taxes each pay period in isolation rather than looking at your year-to-date totals. It often over- or under-deducts and is meant to be temporary. We cover it in detail in the emergency tax code guide.

The S and C prefixes — Scotland and Wales

A prefix changes which band table payroll uses, not how the number and letter are read:

• S (e.g. S1257L) — you pay Scottish Income Tax, which has more bands than the rest of the UK. Scotland also adds two extra flat-rate codes, D2 (Advanced) and D3 (Top).
• C (e.g. C1257L) — the Welsh Rates of Income Tax apply. For 2026/27 these are set to match the rest-of-UK rates, so the take-home is the same; the prefix is mainly an administrative marker.

Quick reference — the codes you'll actually see

A condensed cheat-sheet. To see any of these against your own salary, type the code into the Salary Calculator and watch the deduction lines move.

• 1257L — standard, full £12,570 allowance.
• 1257 W1/M1 — emergency, non-cumulative.
• 0T — no allowance, taxed through the bands from £0.
• BR — flat 20% on everything (typical second job).
• D0 / D1 — flat 40% / 45% on everything.
• K### — negative allowance; 50%-of-pay cap.
• M / N — Marriage Allowance received / given.
• S / C prefix — Scottish / Welsh rates.
• NT — no tax deducted.

How to check — and fix — your tax code

Your code appears on every payslip, your P45, your P60 and inside your HMRC personal tax account. If your main job is on BR, 0T or an unexpected K code, give your employer a P45 or complete the starter checklist, then contact HMRC. Any income tax you've overpaid on a wrong code is repaid automatically through your pay once the correct cumulative code is applied — or after the tax year ends if it isn't corrected sooner.