Understanding your tax code: What the letters and numbers mean

Published Tuesday 20 October 2026

Table of contents

• Understanding your tax code: What it is and why it matters
• What the numbers in your tax code mean
• What the letters in your tax code mean
• What emergency tax codes mean
• Where to find your tax code
• How to check if your tax code is correct
• What your tax code means if you're self-employed
• Stay on top of your tax with Xero
• FAQs on tax codes

Key takeaways

• Your tax code tells your employer or pension provider how much tax-free income you can receive before Income Tax applies.
• The numbers are your tax-free allowance divided by 10, so 1257 means £12,570, while the letters describe your personal situation.
• 1257L is the standard code for the 2026/27 tax year if you have one job or pension and the full Personal Allowance.
• Codes can be wrong, so checking yours through your Personal Tax Account helps you avoid paying too much or too little tax.

Understanding your tax code: What it is and why it matters

A tax code is a short mix of numbers and letters that HMRC gives to your employer or pension provider. It tells them how much of your income you can receive tax-free before Income Tax applies.

Think of it like a setting on a tap. The code controls how much tax is held back from each payslip, so getting it right keeps the flow steady across the year. If the setting is off, you can end up paying too much or too little without realising.

Your tax code primarily covers income taxed through Pay As You Earn (PAYE), such as a salary or a pension. Sole traders earning more than £1,000 a year report profits through Self Assessment instead, so understanding your tax code matters most for any employed or pension income you draw.

What the numbers in your tax code mean

The numbers show your tax-free allowance for the year. Multiply them by ten and you get the amount you can earn before Income Tax starts.

Take the standard 2026/27 code, 1257L. The 1257 becomes £12,570, which is the full Personal Allowance for the year. So someone on tax code 1257L can earn £12,570 before any Income Tax is due.

HMRC adjusts the number up or down to reflect your situation. Company benefits like a car, untaxed income, or tax you still owe from a previous year can all lower the figure, which is why your code may not always read 1257. Earning over £100,000 lowers it too, as your Personal Allowance drops by £1 for every £2 earned above that, and disappears entirely once your income reaches £125,140.

What the letters in your tax code mean

The letters explain how your allowance is worked out and which rate applies to your income. Here's what the common ones mean, according to HMRC guidance on tax codes:

• L: You get the standard tax-free Personal Allowance.
• M: You've received a Marriage Allowance transfer from your partner.
• N: You've transferred part of your allowance to your partner under Marriage Allowance.
• T: Your code includes other calculations used to work out your allowance.
• 0T: You have no tax-free allowance, or HMRC is missing the details needed to give you one.
• BR: All the income from this job or pension is taxed at the basic rate of 20%.
• D0: All the income from this job or pension is taxed at the higher rate of 40%.
• D1: All the income from this job or pension is taxed at the additional rate of 45%.
• NT: You're paying no tax on this income.
• K: Your untaxed income is more than your tax-free allowance, so extra tax is collected.

Scottish and Welsh tax code prefixes

Where you live can change the front of your code, because Income Tax rates differ across the UK. Two prefixes tell your employer which rates to apply.

If you live in Scotland, your code starts with S, so Scottish Income Tax rates apply to what you earn. Scotland has six bands rather than three, so the D-codes mean different things there: SD0 is the intermediate rate, SD1 the higher rate, SD2 the advanced rate, and SD3 the top rate.

If you live in Wales, it starts with C, which stands for Cymru. Welsh rates currently match those in England and Northern Ireland, so the rest of the code works the same way.

What emergency tax codes mean

An emergency tax code is a temporary code HMRC uses when it doesn't yet have full details about your income. You'll usually spot it as W1, M1, or X on your payslip.

These codes are non-cumulative, so each pay period is taxed on its own rather than across the whole year to date. That can mean paying a bit too much or too little tax at first. You often get one after starting a new job without a P45, or when your new employer doesn't yet have the details HMRC needs.

The good news is that an emergency code is rarely permanent. Once HMRC has your full details, it issues your correct code and any tax you overpaid is refunded through your pay.

Where to find your tax code

Your tax code shows up in several everyday places, so you rarely have to go looking far. Check any of the following:

• your payslip, usually near your National Insurance number
• your P45, if you've recently left a job
• your P60, which sums up your pay and tax for the year
• your PAYE coding notice (P2), which HMRC sends when your code changes
• the HMRC app or your Personal Tax Account online

How to check if your tax code is correct

Checking your tax code is worth a few minutes, because a wrong code affects your take-home pay straight away. Work through these steps to confirm yours looks right.

1. Find your current code on your payslip, P60, or coding notice.
2. Compare it against your circumstances, such as whether you have one job, a second job, or any company benefits.
3. Sign in and check how your tax code was worked out using HMRC's online tax code checker.
4. Contact HMRC if the code doesn't match your situation, giving them the details they need to update it.

If you've overpaid, HMRC refunds the difference, often through your pay or a rebate. If you've underpaid, it usually collects the shortfall by adjusting your code so a little more tax comes off over the coming months.

What your tax code means if you're self-employed

If you work for yourself, your business profits aren't taxed through a tax code at all. You report them through Self Assessment and pay tax on your profits after the return is filed.

A tax code still matters when you draw PAYE income alongside your self-employment. That might be a salary from your own limited company, a part-time job, or a pension. Plenty of tradies, freelancers, consultants, and landlords sit in exactly this spot, so it's common to juggle both.

You don't need to be an accountant to keep this straight. Your PAYE income uses a tax code as normal, your profits go through Self Assessment, and HMRC often tweaks your code to collect any tax due on untaxed income. Keeping tidy records of both makes each year far easier, especially as Making Tax Digital for Income Tax rolls out.

Stay on top of your tax with Xero

Getting your head around your tax code is easier when your income and expenses are already organised in one place. Xero helps you keep clear, up-to-date records, track what you earn from every source, and feel ready when tax time comes around. See how accounting software can take the guesswork out of your numbers, and get one month free.

FAQs on tax codes

Here are quick answers to some of the most common questions people ask about their tax codes.

What does the L mean on your tax code?

The letter L means you're entitled to the standard tax-free Personal Allowance. It's the most common letter and appears in the default 1257L code for the 2026/27 tax year.

What's the difference between tax code 1250L and 1257L?

The difference is the Personal Allowance behind each code. 1250L reflected an allowance of £12,500 used in earlier tax years, while 1257L reflects the current £12,570 allowance.

Which tax code is 40%?

The D0 code taxes all the income from that job or pension at the higher rate of 40%. It often applies to a second income when your allowance is already used up elsewhere.

How do you use a tax code checker?

Sign in to your Personal Tax Account on GOV.UK and open the Income Tax section, where HMRC's tax code checker shows your current code and how it was worked out. If it looks wrong, you can update your details there and ask HMRC to review it.