Tax Codes Explained: What 1257L Means and How to Check Yours Is Right

Your tax code tells your employer or pension provider how much tax-free pay you are allowed before Income Tax is deducted. For 2026/27 the standard code is 1257L, which gives the full £12,570 personal allowance. Codes with other numbers or letters mean HMRC has adjusted that allowance for a second income, a company benefit, an underpayment or a change in circumstances. This guide explains what each part means and how to put a wrong code right.

How a tax code works

HMRC works out how much you can earn tax-free in the year, turns it into a code, and sends the code to whoever pays you. Your employer's payroll software spreads the allowance across the year and taxes the rest using the standard bands. Employers do not decide the code and cannot change it; only HMRC can. You see the code on each payslip, on your P60 at year end and on a P45 when you leave a job.

What 1257L means

The number is your tax-free allowance divided by ten and rounded down: 1257 means £12,570. The letter L means you are entitled to the standard personal allowance. A code of 1257L on a monthly payroll gives roughly £1,048 of tax-free pay each month. The allowance has been frozen at £12,570 since 2021 and is due to stay there until April 2031, so this code has been the standard for several years.

The letters explained

• L Standard personal allowance.
• M You receive 10% of your partner's allowance under Marriage Allowance.
• N You have transferred 10% of your allowance to your partner.
• T HMRC needs to review the code, often because the allowance is being tapered (income over £100,000) or the calculation is unusual.
• 0T No allowance at all. Common when a new employer has no P45 and you did not complete a starter checklist.
• BR All income taxed at the basic rate, 20%. Used for second jobs and pensions.
• D0 All income taxed at the higher rate, 40%.
• D1 All income taxed at the additional rate, 45%.
• NT No tax deducted, for example some non-residents.
• S prefix: Scottish rates apply. C prefix: Welsh rates apply.

K codes: when deductions exceed your allowance

If the things HMRC needs to collect through your pay (a company car, medical insurance, the state pension, or tax underpaid in an earlier year) add up to more than £12,570, there is no allowance left to give. Instead, HMRC issues a K code that adds a notional amount to your taxable pay. K300 adds £3,000 a year. Payroll cannot take more than half your gross pay in tax under a K code, which protects people with very large adjustments.

Emergency tax codes: W1, M1 and X

A code ending in W1 (weekly), M1 (monthly) or X is non-cumulative: each pay period is taxed on its own, ignoring what has happened earlier in the year. New starters without a P45 often get 1257L M1. The allowance is correct but no earlier overpayment or underpayment is corrected, so the figure can be out until HMRC issues a cumulative code. Any tax overpaid during the emergency period is refunded through your pay once the proper code arrives, or after the year end.

Why your tax code changes

• Starting or leaving a job, or taking a second one.
• A company benefit starting or stopping, reported by your employer on a P11D or through payrolling.
• HMRC collecting tax underpaid in an earlier year, up to £3,000 through the code if you file Self Assessment.
• Claiming Marriage Allowance or job expenses.
• Starting to receive the state pension, which is paid gross and taxed through your other income.
• Your income passing £100,000, where the allowance reduces by £1 for every £2 above that.

HMRC sends a P2 coding notice when the code changes, by post or to your online account. Read it; the notice lists each adjustment and that is where errors are easiest to spot.

How to check and correct your tax code

Open the HMRC app or your personal tax account and go to "check your Income Tax". It shows the code for each job or pension, the estimated income HMRC is using and every adjustment. If the income estimate is wrong, a benefit has ended, or an old job still appears, update it there and HMRC recalculates the code. Employers normally receive the new code within a couple of weeks.

If you have overpaid in an earlier year, HMRC will usually issue a P800 calculation automatically after the year end. Our guide to claiming a tax refund explains the options.

What Cloudkeepers can do

Directors who take a salary from their own company are often on the wrong code because HMRC has guessed at dividend or benefit income. As part of our payroll service we check the codes HMRC issues against what we know about your income, and query anything that will lead to a surprise bill. If you also file a tax return with us, we reconcile the two at year end.