UK Tax Codes Explained

What does 1257L mean?

1257L is the usual code for someone with one job or pension and the standard £12,570 Personal Allowance. The numbers normally indicate the tax-free income allocated to that employment: multiply them by 10 for an approximate annual amount. L means you are entitled to the standard tax-free Personal Allowance.

The code is not proof that your overall tax position is correct. Other income, benefits, unpaid tax or an allowance adjustment can change the code HMRC issues.

A worked example: code versus estimate

For 2026/27, assume £35,000 annual employment income in England, a full £12,570 allowance, regular pay, no pension or student loan and employee NI category A. Taxable income is £35,000 − £12,570 = £22,430. Income Tax at 20% is £4,486 and annual-estimate NI at 8% is £1,794.40, leaving £28,719.60 a year, or £2,393.30 a month.

With BR applied to that job, all its pay is taxed at the basic rate instead of receiving an allowance through that job. BR may be appropriate for a second job where the allowance is used elsewhere; it does not necessarily mean you are being overtaxed. Our calculator assumes a standard allowance and cannot reproduce every tax code.

Common letters and codes

L: Standard tax-free Personal Allowance.
M / N: M means you receive a transfer of 10% of your partner’s allowance under Marriage Allowance. N means you have transferred 10% of your allowance to your partner.
T / 0T: T means other calculations are included in your Personal Allowance. 0T means your allowance is used up, or your employer does not have the details needed to issue a code. 0T is not a flat-rate code: the relevant tax bands still apply.
BR / D0 / D1: All income from that job or pension is taxed at the basic, higher or additional rate respectively. Scottish variants use different rates; check the full code with HMRC rather than interpreting the suffix alone.
NT: No tax is paid on income from that job or pension under this code.
K: Income or adjustments not taxed elsewhere exceed your allowance, so an amount is added to taxable pay. HMRC limits tax collected through a K code to half of pre-tax pay or pension for that period.

Scottish and Welsh prefixes

S at the start means Scottish Income Tax applies, for example S1257L. C means Welsh Income Tax applies, for example C1257L. These prefixes identify the applicable tax system, not a separate allowance. Our calculator uses Scottish bands when you select Scotland; England, Wales and Northern Ireland share the configured rates for 2026/27.

Emergency codes: W1, M1, X or NONCUM

These markers mean tax is calculated using just that week’s or month’s pay rather than the running totals for the tax year. This can happen after starting a job when the employer does not yet have your previous pay and tax details. 1257L on its own is not an emergency code.

Emergency treatment can cause a difference from an annual estimate, but it does not always mean you have paid too much. The result depends on your income, earlier pay and the information HMRC holds.

What to do if your code looks wrong

Find the full code on your payslip, P45 or HMRC account, including any prefix or emergency marker.
Check HMRC’s records for your jobs, pensions, estimated income and company benefits.
Use HMRC’s tax-code checker and follow its instructions to report incorrect details. Ask payroll whether it has received the latest HMRC code.

A take-home calculator cannot confirm that your personal code is correct or request a refund for you. Do not share your National Insurance number or HMRC sign-in details through our contact form.

Related calculations

Sources and scope

Checked against HMRC’s code meanings and emergency-code guidance on 17 October 2026. The worked example uses 2026/27 rules. General information, not personal tax advice.