UK PAYE tool

Tax Code Decoder Pro

Paste any UK tax code. We break down the allowance, the suffix letter, and whether HMRC is treating you as cumulative or on an emergency basis. 2026/27 thresholds.

What a result looks like

Input: K475

K - Negative allowance

Adds £4,750 to your taxable pay each year. Often used to recover untaxed benefits.

What we check

Numeric portion - implied annual allowance.
Suffix letter (L, M, N, T) - personal circumstance.
Special prefixes (BR, D0, D1, NT, K, 0T).
Emergency markers (W1, M1, X).

When to use this tool

You started a new job.
HMRC sent you a coding notice (P2).
Your tax code changed without obvious reason.
Your take-home dropped suddenly.

What the result bands mean

Standard

Code looks normal for the suffix shown.

Worth reviewing

Code has features (BR, K, 0T) that may indicate something to check.

Possible issue

Code looks unusual - cross-check with HMRC.

Common mistakes

Reading W1 or M1 as part of the number.
Assuming a BR code on a second job is wrong - it usually is not.
Forgetting that K codes recover items HMRC has flagged elsewhere.

Worked example

Code 1257L W1: standard allowance £12,570 but non-cumulative. Each pay period is taxed in isolation.

Often issued to new starters before P45 details are processed - usually corrected within a few pay periods.

Frequently asked questions

What is the standard tax code for 2026/27?

1257L is standard for one job, full personal allowance of £12,570.

Why did my tax code change?

HMRC changes codes when income, benefits, or marriage allowance changes. A change does not always mean an error.

What does W1 / M1 / X mean?

Non-cumulative or 'emergency' codes. Each pay period is taxed in isolation. Often temporary.

Is a K code bad?

Not necessarily - it shows untaxed items being recovered through PAYE. Worth reviewing if unexpected.

Can my employer change my tax code?

No. Only HMRC issues codes. Employers apply what HMRC sends.

Related tools

Last verified: 2026-05-03.

Disclaimer: Educational guidance only. Not tax advice. Always confirm your code with HMRC.