Quick Answer: UK tax codes are combinations of numbers and letters used by HMRC to tell employers how much income tax to deduct from your pay. The most common tax code is 1257L, which means you’re entitled to the standard tax-free Personal Allowance of £12,570. If your tax code is wrong, contact HMRC to correct it and claim any refund you’re owed.
Knowing the list of tax codes and what they mean might seem like a lot to wrap your head around. But they’re vital because they tell you exactly how much you’re paying the government.
Sometimes, they’re incorrect—meaning you could either end up with a nice tax refund or an unexpected bill from HM Revenue and Customs (HMRC).
For that reason alone, it’s worth knowing what tax codes mean, the different tax codes in the UK, and what to do if you’re in the wrong tax code.
Let’s get started.
What is a tax code?
In the UK, a tax code is a combination of numbers and letters issued by HMRC to determine how much income tax should be deducted from an individual’s salary or pension.
It reflects a person’s tax-free allowance and any adjustments for benefits, deductions, or additional income. Employers and pension providers use the tax code to calculate the correct amount of tax to deduct.
How to read a tax code
Understanding your tax code is easier than it looks.
It’s usually a mix of numbers and letters. The numbers show how much tax-free income you’re allowed, while the letters explain any special tax rules that apply to you.
For example, if your tax code is 1257L, it means you get the standard Personal Allowance of £12,570 before you start paying tax.
Get the latest insights and best practice guides, direct to your inbox.
The most common UK tax code
The most common UK tax code is 1257L. This is the standard tax code for most employees and pensioners in the 2026/27 tax year.
The number 1257 represents your tax-free Personal Allowance of £12,570 (multiply the number by 10 to get the allowance amount). The letter L means you’re entitled to the standard tax-free Personal Allowance with no special circumstances affecting your tax.
If you have a straightforward employment situation with one job and no additional taxable benefits, you’ll likely have the 1257L tax code. One thing to be aware of: if your income is over £100,000, your Personal Allowance goes down by £1 for every £2 you earn above that, so your code will be lower.
The list of tax codes and what they mean
Here’s your list of tax codes and what they mean:
| Tax code | Meaning | Explanation |
|---|---|---|
| L | Standard Personal Allowance | You're entitled to the standard tax-free Personal Allowance of £12,570. |
| M | Marriage Allowance | You've received a transfer of 10% of your partner's Personal Allowance. |
| N | Marriage Allowance | You've transferred 10% of your Personal Allowance to your partner. |
| T | Other calculations involved | Your tax code includes other calculations (such as company benefits) to work out your Personal Allowance. |
| S | Scottish taxpayer | Appears at the start of your code (e.g. S1257L). Your income is taxed at Scottish Income Tax rates. |
| C | Welsh taxpayer | Appears at the start of your code (e.g. C1257L). Your income is taxed at Welsh Income Tax rates. |
| 0T | No Personal Allowance or emergency code | Your Personal Allowance has been used up, or you've started a new job and your employer doesn't have the details they need to give you a tax code. |
| BR | Basic rate tax code | All your income from this job or pension is taxed at the basic rate (usually used if you've got more than one job or pension). |
| D0 | Higher rate tax code | All your income from this job or pension is taxed at the higher rate (usually used if you've got more than one job or pension). |
| D1 | Additional rate tax code | All your income from this job or pension is taxed at the additional rate (usually used if you've got more than one job or pension). |
| SD0 | Scottish intermediate rate | All your income from this job or pension is taxed at the Scottish intermediate rate (usually used if you've got more than one job or pension). |
| SD1 | Scottish higher rate | All your income from this job or pension is taxed at the Scottish higher rate (usually used if you've got more than one job or pension). |
| SD2 | Scottish advanced rate | All your income from this job or pension is taxed at the Scottish advanced rate (usually used if you've got more than one job or pension). |
| SD3 | Scottish top rate | All your income from this job or pension is taxed at the Scottish top rate (usually used if you've got more than one job or pension). |
| NT | No tax | You're not paying any tax on this income. |
| W1 | Emergency tax code | Tax is worked out on each week's pay on its own (the "week 1" basis), rather than on your total pay for the year so far. |
| M1 | Emergency tax code | Similar to W1, but for monthly-paid employees: each month is treated as a standalone period. |
| X | Emergency tax code | Works in the same way as W1 and M1: each pay period is taxed on its own, using just that period's share of your Personal Allowance. |
| NONCUM | Emergency tax code | Another way of showing that tax is being worked out on a non-cumulative (period-by-period) basis. |
| K | Income exceeding allowance | You have income that isn't being taxed elsewhere and is worth more than your tax-free Personal Allowance (such as unpaid tax from a previous year or taxable company benefits). |
What’s an emergency tax code?
An emergency tax code is a temporary code that HMRC gives you when they don’t have enough information to work out your correct tax code.
This often happens if you start a new job, move from self-employment to PAYE, or start receiving a company pension. It can also happen if your new employer hasn’t received your P45 from your previous job, or if you haven’t completed a new starter checklist.
Emergency tax codes appear on your payslip at the end of your code (e.g. 1257L W1) as:
- W1 (Week 1): Tax is worked out on each week’s pay in isolation, using just one week’s share of your Personal Allowance rather than your total pay and allowance for the year so far.
- M1 (Month 1): Similar to W1, but for monthly-paid employees; each month is treated as a standalone period.
- X or NONCUM: These work in the same way, showing that your tax is being worked out period by period rather than cumulatively.
These codes can mean you’re paying too much tax (or sometimes too little), but don’t worry—it’s usually sorted once HMRC gets the right details from you or your employer.
What you should do if you’re in the wrong tax code
If you think your tax code is wrong, don’t ignore it—get in touch with HMRC as soon as possible.
You can either:
- Call them on 0300 200 3300
- Log in to your personal tax account online to report the issue.
If you’ve overpaid tax, HMRC will usually update your tax code and let your employer know. The extra tax you’ve paid will be refunded through your wages, so you’ll see a bit more in your payslip. If the overpayment was from a previous tax year, HMRC might send you a cheque instead.
On the other hand, if you’ve underpaid tax, HMRC will want to collect what you owe. If it’s less than £3,000, they’ll likely adjust your tax code so you pay a bit more each month. But if you owe more than that, you’ll probably get a separate tax bill.
Do you still have questions about the different tax codes in the UK?
We know tax codes can be confusing, but you don’t have to figure them out on your own. Whether you’re unsure about your tax code, think it might be wrong, or just want to understand it better, we’re here to help.
Get in touch to see how we can make tax codes (and payroll) simple for you.
Payroll Legislation Guide
The facts, figures, thresholds and allowances for 2025/26 spanning tax, National Insurance, pensions, statutory payments and more.
Frequently asked questions
Q. What does 1257L mean?
A. 1257L is the standard UK tax code, meaning you're entitled to the tax-free Personal Allowance of £12,570 before paying income tax.
Q. How do I check my tax code?
A. You can check your tax code on your payslip or P60, or by logging in to your HMRC personal tax account or the HMRC app.
Q. What is an emergency tax code?
A. An emergency tax code (W1, M1, X or NONCUM) is a temporary code used when HMRC doesn't have enough information to calculate your correct tax. It often results in overpayment.
Q. Why has my tax code changed?
A. Your tax code may change if your Personal Allowance is adjusted, you receive taxable benefits, you have more than one job, or HMRC updates your records.
Q. Can I claim back overpaid tax?
A. Yes. If you've overpaid tax because of a wrong tax code, HMRC will refund you, either through your wages or directly for previous tax years.
