UK Tax Code Checker

Type in your tax code to see what each number and letter means, spot emergency, BR and K codes, and compare your tax with 1257L for 2026/27.

Reviewed by Dany, RightSums team · Updated

Runs in your browser. Free, no sign-up.

salary-tax · Daily life · UK

Enter the tax code from your payslip, such as 1257L, S1257L M1, BR, 0T, D0 or K475, and the checker explains each part in plain English: the tax-free amount, the letter, any S or C prefix for Scotland or Wales, and emergency markers like W1, M1 or X. Add your yearly pay and it estimates your 2026/27 Income Tax under that code and shows how much more or less that is than the standard 1257L code, band by band. It flags things worth checking, such as a BR or 0T code on your only job, a K code near the 50% limit, or an emergency code after starting a job mid-year. Everything runs in your browser and nothing is sent to HMRC.

Accepted inputs

  • Tax code (for example 1257L, S1257L, C1257L, BR, 0T, D0, SD2, K475, NT, 1257L M1)
  • Yearly pay from the job before tax (optional)
  • Pay frequency: weekly, fortnightly, four-weekly, monthly or yearly
  • Month the job started, for emergency codes

Outputs

  • Plain-English meaning of each part of the code
  • Tax-free pay at this job
  • Estimated yearly and per-payday Income Tax for 2026/27
  • Difference compared with 1257L, S1257L or C1257L
  • Tax by band
  • Warnings for emergency, BR, 0T, K and NT codes
  • Emergency code overpayment when you start part-way through the year

How to use the UK Tax Code Checker

  1. Type your tax code exactly as it appears on your payslip or HMRC letter, including any S or C at the start and any W1, M1 or X at the end.
  2. The checker splits the code into its parts and explains each one using HMRC's published meanings, including the tax-free amount the number stands for.
  3. If you add your yearly pay and how often you are paid, it works out your 2026/27 Income Tax under that code and under the standard 1257L code for the same part of the UK.
  4. Read the warnings to see whether the code looks right for your situation, then use HMRC's Check your Income Tax service to fix anything that is wrong.

Frequently asked questions

What does my tax code mean?

The number is your tax-free pay at that job with the last digit dropped, so 1257 means £12,570. The letter describes your situation: L is the standard allowance, M and N are Marriage Allowance, and T means HMRC needs to review it. S means Scottish rates and C Welsh rates. BR, D0, D1, 0T and NT tax all pay the same way.

Why am I on a BR tax code?

BR usually means this is your second job or pension and your main job already uses your £12,570 allowance, so every pound here is taxed at 20%. On £20,000 that is £4,000 a year, against £1,486 under 1257L. If BR is on your only job, you are overpaying and should update your details with HMRC.

What is an emergency tax code?

A code ending in W1, M1 or X (or NONCUM on your payslip) is an emergency code. Tax is worked out on each payment alone. Start a £25,000 job in October with no other pay since April and 1257L M1 takes about £1,243 by 5 April, when the cumulative basis would take nothing. HMRC usually fixes it within 35 days.

What does 0T mean on my payslip?

0T means you get no tax-free pay at that job, so all of it is taxed from the first pound. On £30,000 that is £6,000 a year, compared with £3,486 on 1257L. It is normal if another job uses your allowance or you earn over £125,140, but it can also be a temporary code for a new starter.

How do I change my tax code if it is wrong?

Sign in to HMRC's Check your Income Tax service and update your job, pension, benefit or expenses details. HMRC then tells you and your employer the new code within 15 working days. If you cannot go online, call the Income Tax helpline on 0300 200 3300. After starting a new job, wait 35 days first.

Sources

The rates and rules in this tool come from:

Guides that use this tool

Terms explained

  • Emergency tax code: An emergency tax code, marked W1, M1 or X, taxes each payday on its own, as if you were paid that amount every period of the year.
  • P11D: A P11D is the form UK employers send HMRC by 6 July to report each employee's taxable benefits and expenses that were not taxed through payroll.
  • P45: A P45 is the form your employer gives you when you leave, showing your leaving date, pay and tax so far in the tax year, and your tax code.
  • P60: A P60 is the yearly summary of your pay and tax from one employer, due by 31 May if you work there on 5 April.
  • Personal Allowance: The Personal Allowance is the income you can earn each UK tax year before Income Tax starts: £12,570 for 2026/27.
  • Tax code: A UK tax code tells your employer or pension provider how much tax-free pay to give you; 1257L, meaning £12,570, is the most common.

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