Tax Code Checker — HMRC Code Lookup
Enter your HMRC tax code and find out what it means, your Personal Allowance and if it's correct.
By Konstantin Iakovlev · Founder, Calks.uk
Last updated: · Verified against HMRC and GOV.UK 2026/27 rates
Find your tax code on your payslip, P45, P60 or HMRC letter
1257L
What this means:
Standard tax code — you get the standard Personal Allowance
Disclaimer
This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.
How It Works
Your HMRC tax code tells your employer how much income to treat as tax-free before applying income tax. The most common code is 1257L, meaning you have the standard Personal Allowance of £12,570 for 2026/27. The numbers represent your tax-free entitlement divided by 10, so 1257 means £12,570.
Letter suffixes modify how your allowance works. L means the standard Personal Allowance. M and N are used for Marriage Allowance (M = recipient, N = transferor). T means HMRC needs more information. S means Scottish rates apply; C means Welsh rates. Prefix K indicates a negative allowance — you have untaxed income or benefits that exceed your allowances, so extra tax is collected on top of your salary.
Emergency codes (W1, M1, X) mean each pay period is taxed independently rather than cumulatively. Code 0T means no Personal Allowance at all. Code BR, D0 or D1 apply a flat 20%, 40% or 45% rate to all earnings — typically used for secondary employment.
What does my tax code mean? The number × 10 = your annual tax-free allowance. 1257L = £12,570 Personal Allowance (the standard for 2026/27). The letter indicates your situation: L (standard), M (Marriage Allowance received), N (Marriage Allowance given), T (HMRC reviewing your tax affairs), 0T (no allowance — usually means HMRC has zero info), BR (Basic Rate on all earnings — typical second job), D0 (Higher Rate on all), D1 (Additional Rate on all), NT (no tax — typically diplomats or non-residents).
Why your tax code might be wrong. Common errors: P11D benefit not removed when you change jobs (still being deducted for old car/health insurance); pension contribution not reflected; State Pension included but you're under SPA; underpayment from previous year being recovered too aggressively; multiple jobs producing two BR codes; emergency 1257L M1 code when starting a job (treats each payment as independent — usually under-deducts).
K codes — when deductions exceed allowances. A K code (eg K500) means HMRC is collecting tax on £5,000 extra beyond your salary — usually because of: large taxable benefits (company car, fuel benefit, private health), pension over-funding charges, unpaid tax from previous year, State Pension received in current employment. K codes cannot reduce your take-home below 50% of gross. If you have K600+ you're paying significant 'invisible' tax — investigate why with HMRC directly.
How to fix a wrong tax code. (1) Check your code on gov.uk/personal-tax-account; (2) Use 'Tax Code Checker' tool — explains current code; (3) If wrong, call HMRC on 0300 200 3300 with: NI number, employer details, breakdown of any benefits. (4) Form P87 for tax relief on work expenses; (5) Form P50 if you've stopped work mid-year. HMRC usually corrects within 1-2 weeks. Refunds of overpaid tax come through your salary automatically once corrected, or via P800 letter.
Example: Decoding tax code 1257L
- Numbers 1257 → tax-free amount = 1257 × 10 = £12,570
- Letter L → standard Personal Allowance, England/Wales/NI tax rates
- Monthly tax-free income = £12,570 ÷ 12 = £1,047.50
- Income above £1,047.50/month taxed at 20%, 40% or 45%
Frequently Asked Questions
- What does tax code 1257L mean?
- Tax code 1257L is the most common UK tax code for 2026/27. The number 1257 means your tax-free Personal Allowance is £12,570 (1257 × 10). The letter L confirms you have the standard allowance with no additional adjustments.
- What does my tax code mean?
- Number × 10 = your annual tax-free allowance. 1257L = £12,570 Personal Allowance (standard 2026/27). Letters indicate situation: L (standard), M (Marriage Allowance received), N (Marriage Allowance given), T (HMRC reviewing), 0T (no allowance), BR (Basic Rate on all earnings — typical second job), D0 (Higher Rate on all), D1 (Additional Rate on all), NT (no tax).
- K codes — when deductions exceed allowances.
- K code (e.g. K500) means HMRC collecting tax on £5,000 extra beyond your salary — usually because of: large taxable benefits (company car, fuel benefit, private health), pension over-funding charges, unpaid tax from previous year, State Pension received in current employment. K codes cannot reduce take-home below 50% of gross. K600+ means significant invisible tax — investigate with HMRC.
- How to fix a wrong tax code.
- (1) Check code on gov.uk/personal-tax-account; (2) Use Tax Code Checker tool — explains current code; (3) If wrong, call HMRC 0300 200 3300 with NI number, employer details, benefits breakdown; (4) Form P87 for tax relief on work expenses; (5) Form P50 if stopped work mid-year. HMRC usually corrects within 1-2 weeks. Refunds come through salary automatically once corrected, or P800 letter.