Tax Code 1257L Explained: What It Means and How to Check Yours is Correct

Your tax code tells your employer how much tax to deduct from your pay. If it is correct, you pay exactly the right amount of tax throughout the year. If it is wrong, you could be significantly overpaying — or underpaying — without realising it. In 2026/27, the standard code for most UK employees is 1257L. This guide explains exactly what that means, what all the common variations indicate, and — critically — how to check that your code is right and what to do if it is not.

What Does 1257L Mean?

Breaking It Down

1257L consists of two parts: a number and a letter.

The number — 1257

Multiply the number by 10: 1,257 × 10 = £12,570. This is your tax-free Personal Allowance for the 2026/27 tax year — the amount of income you can earn before paying any income tax.

HMRC divides the Personal Allowance by 10 to create the code number because historically codes were used to indicate tenths of a pound, and the shorthand has persisted.

The letter — L

The letter L means you are entitled to the standard Personal Allowance, with no adjustments. It is the most common suffix — assigned to the majority of UK employees.

So in full: 1257L = £12,570 tax-free allowance, standard terms.

How It Affects Your Pay Packet

With tax code 1257L on a weekly or monthly payroll, your employer divides your allowance evenly across the pay periods:

• Monthly payroll: £12,570 ÷ 12 = £1,047.50 tax-free per month
• Weekly payroll: £12,570 ÷ 52 = £241.73 tax-free per week

Any earnings above this threshold within each pay period are taxed at the basic rate (20%), higher rate (40%), or additional rate (45%) depending on your total income.

The Most Common Tax Code Letters and What They Mean

Emergency and Restricted Tax Codes

These codes are used when HMRC does not hold enough information to assign your correct code.

BR — Basic Rate

BR taxes all income from that employment at 20%, with no Personal Allowance applied to that income source. It is typically assigned when:

• You have a second job (HMRC assumes your allowance has already been used against your main job)
• You start a new job and your previous P45 has not yet been processed
• HMRC has issued it incorrectly

If BR is applied to your main — or only — job, you will overpay tax. On a £30,000 salary: standard code 1257L results in £3,486 income tax; BR code results in £6,000 income tax. Overpayment: £2,514.

D0 — Higher Rate on All Income

D0 taxes all income from that employment at 40%, with no allowance. This should only be used for a second job or income source where you are a higher-rate taxpayer. If applied incorrectly to a main job, the overpayment will be severe.

D1 — Additional Rate on All Income

D1 taxes all income at 45%. Used for a third source of income or where someone's overall income is above £125,140. Incorrect assignment here is rare but costly.

0T — Zero Allowance

The 0T code applies zero Personal Allowance, meaning all income is taxed from the first pound. Tax is collected at all applicable rates (20%, 40%, 45%) across the relevant bands, but no allowance is given. It may be applied when:

• You have started a new job without providing a P45
• Your allowance has been fully used up by other income adjustments
• It has been issued as an emergency code while HMRC processes your records

Example cost on a £40,000 salary with 0T code:

On £40,000 with 0T applied erroneously, you would overpay approximately £2,014 per year in income tax.

NT — No Tax

NT means no tax is deducted at all. Used for individuals who are not liable to UK tax — for example, some non-resident workers or those with specific income types. If you see NT on your payslip and you are a resident UK employee, contact HMRC immediately.

W1 and M1 — Week 1 / Month 1 Emergency Codes

W1 (week 1) or M1 (month 1) added to a code means it is operating on a non-cumulative basis. Normally, PAYE operates cumulatively — if you are overtaxed in April, this is corrected automatically in May. A W1/M1 emergency code treats each pay period in isolation, meaning errors do not self-correct throughout the year.

You may see codes like 1257L W1 or 1257L M1. If you have these suffixes, contact HMRC to have them converted to a standard cumulative code.

K Codes

K codes (e.g. K497) indicate that you have income that uses up more than your Personal Allowance — for example, the value of a company car benefit or state pension income received in addition to employment income. With a K code, your employer deducts extra tax from your pay to cover the additional liability.

The number works in reverse: K497 means an additional £4,970 is added to your taxable income, above and beyond your earnings. There is a cap: your employer cannot deduct more than 50% of your gross pay in a single pay period under a K code.

Marriage Allowance: The M and N Codes

The Marriage Allowance allows one partner in a marriage or civil partnership to transfer 10% of their Personal Allowance (£1,257 in 2026/27) to the other, provided:

• The transferring partner earns below the Personal Allowance (or has no income)
• The receiving partner is a basic-rate taxpayer (earning £12,570–£50,270)

Result: The receiving partner's code becomes 1383M (£13,830 allowance), saving them up to £252 per year in tax. The transferring partner's code becomes 1131N (£11,310 allowance).

To apply: use HMRC's online service at gov.uk/apply-marriage-allowance. It can be backdated up to 4 tax years.

The Scottish and Welsh Prefix

S codes (e.g. S1257L) are used for Scottish taxpayers. Scotland sets its own income tax rates and bands, which differ from the rest of the UK. In 2026/27 Scotland has six tax bands (Starter, Basic, Intermediate, Higher, Advanced, Top) with different thresholds.

C codes (e.g. C1257L) are used for Welsh taxpayers. The Welsh rate of income tax mirrors the UK rate for 2026/27, but the Welsh Government has the power to vary it. Your payslip will show a C prefix if HMRC has you registered as a Welsh taxpayer.

Why Tax Codes Change

Your code may change during the year if:

• You start a new job or leave one
• HMRC adjusts your allowance to collect underpaid tax from a previous year
• You receive a taxable benefit in kind (company car, private medical insurance, etc.)
• Your income changes significantly
• You apply for Marriage Allowance
• HMRC receives information from your employer (P11D) updating your benefits

HMRC sends a PAYE Coding Notice (P2) by post or via your Personal Tax Account when your code changes. Always check these notices.

How to Check Your Tax Code

Via Your Payslip

Your current tax code appears on every payslip. If you are employed in two jobs, you will have a different code from each employer.

Via the HMRC Personal Tax Account

Log in to your Personal Tax Account at gov.uk/personal-tax-account. This shows your current and previous tax codes, explains any adjustments, and allows you to update certain details.

Via the HMRC App

The free HMRC app (iOS and Android) shows your current tax code, estimated tax for the year, and recent income figures reported by your employers.

How to Correct a Wrong Tax Code

Step 1: Identify the Error

Common errors include:

• Old benefits still showing on your code after they ended
• Wrong tax code from a new job (emergency code not updated)
• Marriage Allowance not applied or incorrectly applied
• Unpaid tax from a previous year being collected incorrectly

Step 2: Contact HMRC

You can correct your tax code:

• Online: Through your Personal Tax Account — many adjustments can be made instantly
• By phone: HMRC Income Tax helpline: 0300 200 3300 (Monday–Friday, 8am–6pm)
• By post: PAYE and Self Assessment, HMRC, BX9 1AS

When contacting HMRC, have your National Insurance number, employer details, and P60/payslip to hand.

Step 3: Reclaim Overpaid Tax

If your code has been wrong during the current tax year, your tax bill should self-correct through the cumulative PAYE system once the right code is in place — you will see lower tax deductions in future months. If the tax year has ended, HMRC will automatically issue a P800 tax calculation (usually by September after the tax year ends) if they believe you have overpaid. The P800 will confirm how to claim a refund — either online (paid within 5 days) or by cheque (up to 60 days).

You can also claim a refund proactively via your Personal Tax Account.

P800: If You Have Overpaid Tax

HMRC sends P800 letters when their records indicate a discrepancy between tax paid and tax owed. If you receive a P800 saying you are owed a refund:

• Check the calculation carefully — HMRC's information may not be complete
• If correct, claim online via your Personal Tax Account (refund paid within 5 days)
• If incorrect, contact HMRC to discuss before accepting

You can also check whether you are owed a refund by using HMRC's tax checker at gov.uk/check-if-you-need-to-send-a-self-assessment-tax-return or by reviewing your Personal Tax Account.

Quick Reference: Common Tax Codes and What They Cost

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Use our Take-Home Pay Calculator or Income Tax Calculator to enter your tax code and see exactly how much tax should be deducted from your salary — and how much you would save by correcting a wrong code.