Moonworkers
2026-27 · HMRC exact percentage method

UK Tax Code Checker

What your tax code means, and the exact tax-free pay it gives you in every pay schedule, computed with the same HMRC routine payroll software uses.

On your payslip, P45 or P60. Suffixes W1, M1 or X welcome.

What you'll get

Enter any UK tax code to see:

  • · what each letter and number means
  • · which nation's rates apply (S and C prefixes)
  • · cumulative vs emergency W1/M1/X basis
  • · the exact tax-free pay for every pay schedule, to the penny

Try 1257L, a K code, or an emergency W1 code.

Payroll that applies every tax code correctly

Moonworkers runs the full HMRC exact percentage method on every payslip, including K codes, emergency codes and in-year code changes, and files RTI automatically.

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Every UK tax code, explained

The full list of letters, prefixes and special codes HMRC uses in 2026-27.

1257L

The standard code for 2026-27: full Personal Allowance of £12,570, taxed cumulatively. Most UK employees have this code.

L

Suffix meaning the standard Personal Allowance applies. The number times 10 approximates the annual allowance.

M / N

Marriage Allowance codes: M received 10% of a partner’s allowance (1383M), N transferred 10% away (1131N).

T

The allowance is adjusted and HMRC reviews the code, commonly when income exceeds £100,000 and the allowance tapers.

BR

All income taxed at the basic rate (20%) with no allowance. Typical for second jobs where the allowance is used elsewhere.

D0 / D1

All income taxed at 40% (D0) or 45% (D1) with no allowance, England, Wales and NI. Scotland uses SD0, SD1 and SD2 for its bands.

0T

No allowance, but normal tax bands apply. Used when a starter declaration is missing or the allowance is exhausted.

K codes

Negative allowance: K475 adds £4,750 of notional pay to taxable income, usually to collect benefits in kind or tax owed. Deductions are capped at 50% of gross pay per period.

NT

No tax deducted at all. Rare, HMRC-directed (some bankruptcy or non-resident cases).

S / C prefix

Scottish (S1257L) or Welsh (C1257L) income tax rates apply, based on where the employee lives, not where they work.

W1 / M1 / X

Emergency, non-cumulative basis: each period taxed in isolation. Common after a job change without a P45, until HMRC issues the correct code.

Help & Guidance

Frequently asked questions

UK tax codes and tax-free pay, based on the HMRC PAYE specification.

What does tax code 1257L mean?
It is the standard UK tax code for 2026-27. The 1257 means a tax-free Personal Allowance of about £12,570 a year (the exact free pay used by payroll is £12,579), and the L means the standard allowance applies. Tax is calculated cumulatively across the year.
How is monthly tax-free pay calculated from a tax code?
Payroll software uses the HMRC exact percentage method: the code number is split into blocks of 500, each part is converted to an annual amount, divided by the number of pay periods and rounded up to the penny. For 1257L that gives £1,048.26 a month, not simply £12,570 divided by 12. This checker shows the exact figure for every schedule.
Why is my tax code BR?
BR taxes all income at the basic rate (20%) with no tax-free allowance. It usually means your Personal Allowance is being used against another job or pension. If this is your only income, contact HMRC because you are probably overpaying.
What is a K tax code?
A K code means negative allowance: instead of tax-free pay, additional notional pay is added to your taxable income, typically to collect tax on company benefits or tax owed from earlier years. K475 adds £4,750 a year. The tax deducted in any period is capped at 50% of that period’s gross pay.
What does W1, M1 or X on my tax code mean?
These are emergency, non-cumulative codes: each week (W1) or month (M1) is taxed on its own, ignoring the year to date. They appear after a job change without a P45. You will not automatically get refunds through the year, so ask HMRC to issue your correct cumulative code.
What are S and C tax codes?
S1257L applies Scottish income tax rates (six bands from 19% to 48%) and C1257L applies Welsh rates (currently matching England). The prefix depends on where the employee lives. National Insurance is UK-wide and unaffected.
Why does 1257L give £12,579 of free pay, not £12,570?
HMRC rounds the code number up: a code of 1257 gives free pay of 1257 times 10 plus 9. This is deliberate, so that nobody on a given code pays tax on their full allowance. It is why annual free pay figures always end in 9.
How do I find my tax code?
It is on your payslip, your P45, your P60, and in your Personal Tax Account on GOV.UK. HMRC also sends a PAYE Coding Notice (P2) when your code changes.
Why did my tax code change?
Common reasons: company benefits like a car or medical insurance (often creating a K code), a second job (BR or D0), Marriage Allowance transfers (M or N), income over £100,000 tapering the allowance (T), or repaying tax owed. HMRC explains the change on your Coding Notice.
Is this the same calculation my payroll software uses?
Yes. The free pay figures come from the HMRC PAYE Tax Table Routines specification (section 3.3.1), the exact percentage method that HMRC-recognised software, including the Moonworkers payroll engine and API, must implement.

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