Most people never check. An incorrect tax code could be costing you hundreds of pounds a year. Follow the 3 steps below to find out — it takes 30 seconds.
| Letter(s) | Meaning | Personal Allowance? |
|---|---|---|
| L | Standard Personal Allowance (most common code) | Yes — standard |
| M | Received 10% of partner's allowance via Marriage Allowance | Yes — increased |
| N | Transferred 10% of your allowance to your partner | Yes — reduced |
| T | Other calculations apply; HMRC reviewing your affairs | Depends |
| 0T | No Personal Allowance — emergency code, new job without P45 | No |
| BR | All income taxed at 20% Basic Rate — common for second jobs | No |
| D0 | All income taxed at 40% Higher Rate — additional jobs/pensions | No |
| D1 | All income taxed at 45% Additional Rate | No |
| NT | No tax to pay on this income | N/A |
| K | Negative allowance — unpaid tax or taxable benefits exceed Personal Allowance | Negative |
| S prefix | Scottish taxpayer — Scottish Income Tax rates apply | Yes (Scottish) |
| C prefix | Welsh taxpayer — Welsh rates of Income Tax apply | Yes (Welsh) |
| W1 / M1 | Emergency code — tax calculated per pay period, not cumulatively | Temporary |
The 1257L tax code is the most common code for the 2026/27 tax year. It signifies that you are entitled to the standard Personal Allowance of £12,570, which is the amount of income you can earn tax-free. If you see this code, it usually means you have one job and no taxable employer benefits.
Your tax code might be wrong if you've recently changed jobs, started receiving a company car, or have multiple sources of income. Common signs of an incorrect code include a sudden drop in take-home pay or being placed on an emergency tax code (like 1257L W1, M1, or X). Use our tax code calculator above to verify your details.
If our checker suggests you are overpaying, you must contact HMRC to update your records. You can do this through your Personal Tax Account online or by calling the HMRC helpline. Once updated, HMRC will issue a new tax code to your employer, and any overpaid tax is usually refunded through your next payslip.
BR (Basic Rate): This usually happens if you have a second job or pension and your entire Personal Allowance is already used up by your main income.
K Code: This means your untaxed income (like company benefits or state pension) is higher than your Personal Allowance. Effectively, you are being taxed on more than your total salary.
Once HMRC is notified of a change, it typically takes 5 to 10 working days for them to process the update and send a 'P6' or 'P9' notice to your employer. Your employer will then apply the new code in the next available payroll cycle.