Tax Code Checker 2026/27 — Decode Your HMRC Tax Code
Your tax code tells your employer how much Income Tax to deduct. HMRC issues new codes each April but errors are common — a wrong code means overpaying or underpaying for an entire year. The most common code is 1257L — the digits represent your £12,570 Personal Allowance, the L means standard allowance.
Other key codes: BR (all at 20%, no allowance — typical for second jobs), D0 (all at 40%), K (negative allowance), W1/M1 (emergency week/month 1 basis).
| Code | Meaning |
|---|---|
| L | Standard tax-free Personal Allowance (e.g. 1257L) |
| M | Marriage Allowance received (10% of partner's allowance) |
| N | Marriage Allowance transferred to your partner |
| T | Other calculations affect your allowance (HMRC review needed) |
| 0T | No Personal Allowance — often emergency, or allowance used up elsewhere |
| BR | Basic rate (20%) on all income, no allowance — common for second jobs |
| D0 | Higher rate (40%) on all income, no allowance |
| D1 | Additional rate (45%) on all income, no allowance |
| K (+ number) | Negative allowance — untaxed income/benefits added on top of your pay before tax |
| NT | No tax deducted — very specific circumstances only |
| W1 / M1 (suffix) | Emergency, non-cumulative basis — each pay period taxed in isolation |
| S (prefix) | Scottish Income Tax rates apply (e.g. S1257L) |
| C (prefix) | Welsh Income Tax rates apply (e.g. C1257L) |
Tax Code Checker: Is Your UK Tax Code Correct?
Your tax code is one of the most important pieces of information on your payslip — yet most people never check it. An incorrect tax code can cost you hundreds or even thousands of pounds in overpaid or underpaid tax. This tool decodes any UK tax code and tells you whether it looks right for your circumstances.
How UK tax codes work
A tax code is usually a number followed by a letter. The number represents your tax-free allowance divided by 10. For example, 1257 means a tax-free allowance of £12,570. The letter indicates your tax situation: L means you get the standard allowance, M means you have received Marriage Allowance from your partner, N means you have transferred Marriage Allowance to your partner, T means your tax code has been adjusted by HMRC, and K means your deductions exceed your allowances.
Emergency tax codes like BR (basic rate on all income), D0 (40% on all income), and 0T (no personal allowance) are temporary but can persist if HMRC does not receive correct information. The W1 and M1 suffixes mean tax is calculated on a "week 1/month 1" basis — essentially emergency tax that does not account for your cumulative income.
Common reasons for wrong tax codes
Tax codes go wrong when you change jobs without a P45, have multiple employments, receive taxable benefits, claim Marriage Allowance, or have underpaid tax in a previous year. HMRC adjusts your code to collect underpaid tax through your salary — look for a reduction in your tax-free amount. If your code changes unexpectedly, call HMRC on 0300 200 3300 or check your Personal Tax Account online.
Common UK Tax Codes Explained
| Code | Meaning | Who It Applies To |
|---|---|---|
| 1257L | Standard Personal Allowance (£12,570) | Most employees with one job |
| BR | Basic Rate (20% on all income) | Second jobs, pensions |
| D0 | Higher Rate (40% on all income) | Second jobs for higher earners |
| NT | No Tax | Non-residents, special cases |
| K1257 | Negative allowance — tax owed | Those with untaxed income exceeding allowance |
| 0T | No Personal Allowance | When allowance is used elsewhere |
| M | Marriage Allowance recipient | Received 10% of partner's allowance |
| N | Marriage Allowance transferrer | Gave 10% of allowance to partner |
| S | Scottish tax rates | Scottish taxpayers |
| C | Welsh tax rates | Welsh taxpayers |
How to Check Your Tax Code
You can find your current tax code in four places:
- Your payslip. It is usually printed near your name or National Insurance number, for example 1257L.
- Your P45 or P60. A P45 shows the code from your last job and a P60 shows your code at the end of the tax year.
- Your HMRC online account. Sign in to your personal tax account, or the HMRC app, and use Check your Income Tax for the current year to see your tax code and how it was worked out.
- A tax code notice. HMRC sends one when your code changes, often just before the new tax year in April.
Type the code into the calculator above to see what it means and compare it with your salary. If it does not look right, see HMRC's guide to tax codes and contact HMRC to ask for it to be corrected.
What Do Tax Code Numbers Mean?
Add a zero to the number in your code to get your tax-free allowance for the year. A lower number means less of your pay is tax-free. These examples are illustrative:
| Code | Tax-free allowance | Why you might have it |
|---|---|---|
| 1257L | £12,570 | The standard code for most employees in 2026/27 |
| 1157L | £11,570 | £1,000 less allowance, for example because of a small taxable benefit or tax underpaid earlier |
| 957L | £9,570 | A larger deduction, for example a company car or unpaid tax being collected |
| 457L | £4,570 | Part of the allowance given to a second job after splitting it between two employers |
| 0T | £0 | No allowance applied, often an emergency or temporary code |
| K475 | minus £4,750 | Untaxed income or benefits larger than your allowance, so £4,750 is added to your taxable pay |
Scottish and Welsh taxpayers see an S or C in front of the code (for example S1257L or C1257L). The number works in the same way, but Scottish and Welsh Income Tax rates are applied.
Why Is My Tax Code Wrong?
Your tax code can be wrong for several reasons. Here are the most common:
- Changed jobs: Your new employer may use an emergency tax code (W1/M1) until HMRC sends the correct one.
- Company benefits: A company car, private medical insurance, or other benefits reduce your tax-free allowance.
- State Pension: If you receive State Pension and work, your code may be adjusted to collect tax on both.
- Under/overpaid last year: HMRC may adjust your current code to collect underpaid tax or refund overpaid tax.
- Multiple incomes: Having a pension and a job, or two jobs, can split your Personal Allowance incorrectly.
What to do: Check your latest tax code notice (P2) from HMRC. If it looks wrong, call HMRC on 0300 200 3300 or use your personal tax account.
Frequently Asked Questions
What does the number in my tax code mean?
The number is your tax-free Personal Allowance divided by 10. For example, 1257 means £12,570 tax-free. If you have deductions (company benefits, unpaid tax), these are subtracted from your allowance, giving a lower number.
How do I know if I'm on the wrong tax code?
Use our calculator above to compare your code against your salary. If the result says "Check needed", you may be underpaying or overpaying. Also watch for: emergency codes lasting more than a month, a K code when you don't have untaxed income, or a BR code on your only job.
What is an emergency tax code?
Emergency codes (ending W1 or M1, or starting with X) mean your employer is taxing you on a "week 1/month 1" basis without your full tax history. You'll usually pay more tax initially, but it corrects once HMRC sends your proper code. It should not last more than 1-2 months.
Sources & Methodology
All calculations are verified against official HMRC thresholds and rates for the 2026/27 tax year. Figures are updated within 24 hours of any HMRC announcement. Calculations are for guidance only — consult a qualified accountant for personalised advice.