Your tax code is the short string of numbers and letters — usually 1257L for 2026/27 — that tells your employer or pension provider how much income tax to take before you are paid. The numbers stand for your tax-free Personal Allowance (1257 means £12,570), and the letter flags your circumstances. The standard code means your full allowance is being applied. If yours looks different, you may be on the wrong code and paying too much – or too little – tax, which you can check and fix.
Related reads: marriage allowance, personal savings allowance, and our take-home pay calculator.
What a tax code is and where to find it
A tax code is an instruction from HM Revenue & Customs (HMRC) to whoever pays you. Under PAYE (Pay As You Earn), your employer or pension provider uses the code to work out how much income tax to deduct each pay period, so the right amount is collected through the year rather than in one bill.
You can find your current code in several places: on your payslip, on your P60 (the end-of-year summary your employer gives you), on a P45 if you have left a job, and in any PAYE Coding Notice (form P2) HMRC posts to you. The quickest way to see it is the free HMRC app or your Personal Tax Account at GOV.UK, where you can also see how the code was calculated.
The standard code 1257L and the £12,570 allowance
Most employed people on a single job are on 1257L. The number is your tax-free Personal Allowance with the final digit removed: 1257 maps to £12,570, the standard allowance for 2026/27. You can earn up to that amount in a tax year before paying any income tax.
The £12,570 allowance has been frozen since 2021 and is set to stay frozen until April 2031. Because it does not rise with inflation or pay, more people are gradually pulled into paying tax — an effect known as fiscal drag — even though the headline figure has not changed. The letter L simply means you get the standard allowance with no special adjustments.
If you live in Scotland your code starts with S (for example S1257L) and in Wales with C (C1257L), reflecting devolved tax rates. The allowance figure is the same UK-wide.
What the letters in your tax code mean
The letter after the number describes your situation. Some letters add or remove allowance; others tell the payer to apply a flat rate to everything. Here is what the common ones mean.
| Code / letter | What it means |
|---|---|
| L | You get the standard tax-free Personal Allowance (the usual code is 1257L). |
| M | Marriage Allowance: you have received 10% of your partner’s allowance. |
| N | Marriage Allowance: you have given away 10% of your allowance to your partner. |
| T | Your code includes other calculations HMRC needs to review (for example a tapered allowance). |
| K | Deductions (untaxed income, benefits or owed tax) exceed your allowance, so tax is added rather than relieved. |
| BR | All income from this source is taxed at the basic rate (20%), with no allowance – common for a second job. |
| D0 | All income from this source is taxed at the higher rate (40%). |
| D1 | All income from this source is taxed at the additional rate (45%). |
| NT | No tax is taken from this income at all. |
| 0T | No allowance is applied; often used when HMRC lacks details, such as a new job with no P45. |
| W1 / M1 / X | Emergency codes applied on a week-1 or month-1 basis, taxing each period in isolation. |
K codes: when deductions are bigger than your allowance
A K code works in reverse. Instead of giving you tax-free pay, it adds an amount to your taxable income because something needs to be collected — commonly a company car or other taxable benefit, the State Pension, or unpaid tax carried over from an earlier year. The number after the K, multiplied by 10, is roughly how much is added to your annual taxable pay. There is a safeguard: a K code cannot take more than 50% of your pay in any single period.
BR, D0, D1 and second jobs
Your Personal Allowance can only be applied once. So if you have two jobs or a job plus a pension, HMRC usually gives the allowance to your main income and applies a flat-rate code to the second. BR taxes the second source at 20%, D0 at 40%, and D1 at 45%. These are not automatically wrong — they are correct if your main job already uses the whole allowance. They become a problem when your circumstances change and the codes are not updated.
Emergency codes: W1, M1 and 0T
When you start a new job without a P45, or your circumstances are unclear, you may be put on an emergency code. Codes ending in W1 (week 1) or M1 (month 1), or shown with an X, tax each pay period on its own rather than cumulatively, which often means too much is deducted at first. 0T applies no allowance at all. Emergency codes are usually temporary: once HMRC has your full details, your code is corrected and any overpayment is repaid through your pay or a P800.
Why your tax code might be wrong
Codes go wrong more often than people expect, usually because HMRC is working from out-of-date or estimated information. Common causes include:
- Multiple jobs or pensions — the allowance is split or duplicated incorrectly.
- Company benefits (BIK) — a car, medical insurance or other perk you no longer receive is still being deducted.
- Untaxed income — rental or savings income estimated too high or too low.
- The State Pension — it is taxable but paid without tax taken off, so it is collected through your code.
- Starting or leaving a job — gaps where an emergency or 0T code lingers.
How a wrong code changes what you pay
Illustrative figures for a single £30,000 salary in 2026/27. On the correct 1257L code, tax is around £3,486 (20% on income above £12,570). On a BR or 0T code the whole £30,000 is taxed with no allowance, costing roughly £6,000 — about £2,500 more a year. The final bar shows what you should be paying; the gap is what a wrong code can cost.
How to check and challenge a wrong code
Start by viewing your code and how it was worked out in the HMRC app or your Personal Tax Account. Check that the benefits, second incomes and estimates listed actually match your situation. If something is out of date — a company car you returned, income you no longer receive — you can update it online, through the app, or by phoning HMRC on the income tax helpline. HMRC then issues a corrected code to your employer, who applies it on your next payday. There is no charge to do this, and you do not need an accountant.
Reclaiming overpaid tax with a P800
After the tax year ends, HMRC checks whether PAYE collected the right amount. If you overpaid — often because of a wrong code — it sends a P800 tax calculation showing the refund and how to claim it, usually online through your Personal Tax Account or by cheque. Always check the figures against your payslips and P60 first. If the P800 looks wrong, contact HMRC to query it. You can claim back overpaid tax for up to four years after the end of the relevant tax year, so it is worth reviewing past years too.
Frequently asked questions
Is 1257L the right tax code for me?
For most people with one job or pension and no extra adjustments, 1257L is correct for 2026/27 — it gives the full £12,570 Personal Allowance. If you have more than one income, company benefits or untaxed income, your code may legitimately differ.
What does a K tax code mean?
A K code means your deductions — such as a taxable benefit, the State Pension or tax owed from a previous year — are larger than your Personal Allowance. Instead of tax-free pay, an amount is added to your taxable income, though no more than 50% of your pay can be taken in any one period.
Why am I on an emergency tax code?
Emergency codes (ending W1, M1 or shown with X, or 0T) are used when HMRC does not yet have your full details — typically after starting a new job without a P45. They usually mean too much tax at first, but the code is corrected once your information is in, and any overpayment is repaid.
How do I get a refund if my tax code was wrong?
If you overpaid through PAYE, HMRC usually sends a P800 calculation after the tax year ends, letting you claim online or by cheque. You can reclaim overpaid tax for up to four years. Always check the P800 against your payslips and P60 before accepting it.
What are the M and N tax codes?
M and N relate to Marriage Allowance. An M code means you have received 10% of your partner’s allowance, lowering your tax. An N code means you have transferred 10% of yours to them. Both only apply where one partner earns below the allowance and the other is a basic-rate taxpayer.
Last reviewed: June 2026. This article is general information, not personal financial or tax advice. Check your own code via GOV.UK or the HMRC app, and seek professional advice for your circumstances.