What Does My Tax Code Mean?

What a tax code is for

Your tax code tells your employer or pension provider how much tax-free income to give you before deducting income tax through PAYE. Get it wrong and you can overpay or underpay tax for months without realising.

It usually appears on your payslip, P45, P60 and any HMRC coding notice. The quickest live check is your Personal Tax Account or the HMRC app.

How 1257L is built

1257L is the standard code for most people in 2025/26. The number is your tax-free Personal Allowance with the last digit removed — 1257 means £12,570 a year tax-free.

The letter shows your situation. L means you get the standard Personal Allowance. Above the allowance, you pay 20%, 40% or 45% depending on how much you earn.

What the letters mean

The letter after the number changes how your pay is taxed:

• L — standard Personal Allowance (most employees)
• M / N — Marriage Allowance received (M) or transferred (N)
• BR — all income from this job taxed at 20% (basic rate), no allowance
• D0 — all income taxed at 40% (higher rate)
• D1 — all income taxed at 45% (additional rate)
• 0T — no Personal Allowance, often used when HMRC lacks details
• K — you have income or benefits that exceed your allowance (see below)
• S or C prefix — Scottish (S) or Welsh (C) tax rates apply

Why BR, D0 and D1 codes happen

BR, D0 and D1 are common on second jobs or pensions, where your Personal Allowance is already used by your main income. They tax the whole of that income at a single rate with no tax-free band.

If you only have one job and you are on BR, you may be overpaying tax — it is worth checking with HMRC.

K codes explained

A K code means deductions (such as company benefits, state pension or tax owed from a previous year) are greater than your Personal Allowance. Instead of tax-free income, an amount is added to your taxable pay.

There is a safeguard: an employer cannot deduct more than half your pre-tax pay through a K code in any pay period.

Emergency tax codes

If you start a job without a P45, you may be put on an emergency code such as 1257L W1, 1257L M1 or 1257L X. These tax each pay period in isolation rather than across the year, so you can overpay.

It usually fixes itself once HMRC receives your details — often via your employer's first submission or your P45 — and any overpayment is refunded through your wages.

Why your tax code changes mid-year

HMRC updates codes when your circumstances change — a new job, company car, taxable benefits, savings interest above your allowance, or repaying tax owed from a previous year.

If you owe tax on savings interest, HMRC often collects it by reducing your Personal Allowance, which lowers the number in your code.

How to check if your tax code is wrong

Compare your code with 1257L and investigate any difference you do not understand. Sign in to the Check your Income Tax service on GOV.UK to see your current code and how HMRC worked it out.

If it is wrong, HMRC usually corrects it automatically once they have the right information, and refunds any overpaid tax through your wages. You can also contact HMRC directly.

See how your code affects take-home pay

Use our PAYE Salary Calculator UK to see how different tax codes — including BR, D0 and D1 — change your estimated tax and monthly take-home pay. General guidance only; check GOV.UK and your payslip for official figures.