What is my tax code

Written by Oroni Chowdhury · Published: November 2026 · Last reviewed: November 2026 · Applies to the 2026/27 tax year

You open a payslip, see something like 1257L M1, and wonder whether it is right, or your first pay from a new job looks lighter than expected. Either way, the question is the same: what is my tax code, and is it correct?

This guide answers “what is my tax code?” in full. It shows where to find your code, how to read it, how to check it and what to do if it is wrong.

What Is My Tax Code? The Short Answer

Your tax code is HMRC’s instruction to whoever pays you: how much of your income is tax-free and which rate to use on the rest under PAYE.

Why HMRC gives you one

HMRC builds the code from your Personal Allowance, company benefits, untaxed income and any tax owed from earlier years. If you have two jobs, or a job and a pension, each one gets its own code.

HMRC normally tells your employer or pension provider which code to use. In a new job, your employer may first use the details on your P45 or starter checklist until HMRC sends or confirms the right code. After that, your employer cannot change an HMRC-issued code on its own.

Income over £100,000 also matters. If your adjusted net income goes above £100,000, your Personal Allowance shrinks by £1 for every £2 over the limit, and it can fall to nothing. So a high earner with a single job may not have 1257L at all.

A tax code is not your other tax numbers

Don’t confuse the code with your National Insurance number, your employer’s PAYE reference or your Unique Taxpayer Reference, which is used for Self Assessment. If that is the number you need, see our guide to finding your UTR.

How Do I Find My Tax Code? 6 Places to Look

If you’re wondering what is my tax code right now, start at the top of this list. The first two show your current code even if HMRC has just changed it.

1. The HMRC app. Shows the current code for each job or pension.
2. Your personal tax account. GOV.UK’s Check your Income Tax for the current year service shows your code and how HMRC worked it out.
3. Your payslip. Usually printed near your National Insurance number.
4. A PAYE coding notice. The letter (often a P2) HMRC sends when your code changes, with the figures behind it.
5. Your P60. Shows the code in use at the end of the tax year.
6. Your P45. Shows the code used on your final payment from a job you left.

What Does My Tax Code Mean? Reading It Part by Part

Once you know what is my tax code, the next step is reading it. Every code is built from up to four parts. Most people only have the middle two.

The number

For most codes with a number, multiply it by 10 to get the approximate tax-free income given to that job or pension for the tax year. K codes are the exception: their number is an amount added to your taxable pay. Codes such as BR, D0, D1 and NT do not use a number in this way at all.

With the full £12,570 Personal Allowance, the code number is 1257. GOV.UK gives the example of a £1,570 company benefit: HMRC takes it off the allowance, leaving £11,000, so the code becomes 1100L. You can see the full method in GOV.UK’s guide on what your tax code means.

The letter

When you ask “what is my tax code?”, the letter is often the part that matters most, because it shows your situation at a glance.

Emergency suffixes: W1, M1 and X

An emergency code is normally a temporary measure. It may be used when you start a job and your employer doesn’t have your full pay and tax details, or when certain company benefits or State Pension payments begin. Under it, tax is worked out on the current pay period alone, not on your total income so far in the tax year. GOV.UK’s page on emergency tax codes says updating a new starter’s code can take up to 35 days.

What Is My Tax Code Telling Me? Four Examples

How Do I Check My Tax Code Is Right?

Knowing what is my tax code is only half the job; checking it is the other half. If HMRC’s information is old or incomplete, the code will be wrong, and it is up to you to spot it. These five questions catch most problems.

1. Do you have more than one job or pension? Only one source normally gets your full allowance.
2. Do you get company benefits? A company car or medical cover usually lowers the number.
3. Do you have untaxed income? Rental income, taxable savings interest, State Pension income or other untaxed income may affect your code. Self-employed profits are normally dealt with through Self Assessment instead.
4. Do you give or receive Marriage Allowance? You should see an N or M.
5. Do you live in Scotland or Wales? Your code should start with S or C.

If all five answers are no and you have one job, expect 1257L. Anything else is worth checking in your personal tax account, which shows how HMRC reached the figure.

A quick pay check

Run this check whenever you look up what is my tax code after a pay change. GOV.UK also has a tool to check if the tax on your payslip is correct.

Two Jobs or a Pension? Why You Have More Than One Code

With two jobs, the honest answer to “what is my tax code?” is that you have two. You only get one Personal Allowance, however many jobs or pensions you have. HMRC normally gives it to your main source of income, and other jobs get BR (taxed at 20%) or D0 if your total income reaches the higher rate band.

HMRC can also split your Personal Allowance between more than one job or pension where that suits your circumstances, for example if your main job pays less than your allowance. Check how it has been shared in your personal tax account rather than assuming it must all sit against one source, and ask HMRC to change it if it looks wrong.

My Tax Code Is Wrong: What to Do

If the answer to “what is my tax code?” doesn’t match your situation, act quickly. Your employer cannot change the code for you, so go straight to HMRC. GOV.UK’s guide on updating your tax code sets out the route.

1. Check your details online in Check your Income Tax for the current year: jobs, pensions, estimated income, benefits and expenses.
2. Update anything wrong or missing. This is the quickest way to get a new code.
3. Wait for HMRC to notify you and your employer. GOV.UK says this usually happens within 15 working days.
4. Look out for the change. On monthly pay it should show on your next or the following payslip. On weekly pay, expect it by the third payslip.
5. Settle the difference. Overpaid tax usually comes back through your pay or a P800; underpaid tax may be collected through a future code.

If you have just started a new job, give your employer your P45 or complete the starter checklist, then allow up to 35 days, as GOV.UK suggests, before contacting HMRC so it can receive your details.

Your Tax Code and Self Assessment

If you file a Self Assessment return as well as being employed, your tax code and your return affect each other. That is why the answer to “what is my tax code?” can change after you file.

Paying a Self Assessment bill through your tax code

HMRC can usually collect a Self Assessment bill through your tax code if you owe less than £3,000, already pay tax through PAYE and file your return in time: by 31 October for a paper return or 30 December for an online one. You also need enough PAYE income to cover the extra deductions.

HMRC won’t use this route if it would take more than 50% of your PAYE income or make you pay more than twice your usual tax. You can’t pay part of a bill of £3,000 or more to bring it under the limit. Where it does apply, your code number falls, or becomes a K code, until the debt is cleared.

Landlords and other side income

HMRC sometimes reduces your code to collect tax on rental profits or other untaxed income, so check it whenever that income changes. Self-employed profits are normally taxed through your Self Assessment return rather than your code.

If you have a job plus property or self-employed income, our online Self Assessment accountants can check your code against your return and make sure you are not taxed twice.

Tax Code Decision Table

Use this once you have answered “what is my tax code?” for each job.

Common Mistakes With Tax Codes

Even after finding out what is my tax code, people often slip up in these ways.

• Blaming your employer: apart from the first weeks of a new job, they apply the code HMRC sends. Changes go through HMRC.
• Not telling HMRC about changes: a new benefit or second job affects your code.
• Forgetting Marriage Allowance: if your relationship or eligibility changes, check with HMRC whether the transfer should be cancelled or updated. Don’t assume your code will change on its own.

FAQs: What Is My Tax Code?

Where do I find my tax code?

Check the HMRC app, your personal tax account, your payslip, a PAYE coding notice, your P60 or your P45.

What is the most common tax code for 2026/27?

1257L. It gives the full £12,570 Personal Allowance to someone with one job or pension and no adjustments. Benefits, untaxed income, old tax owed, an S or C prefix or income over £100,000 can all change it.

Why has my tax code changed?

Usually because HMRC has new information, such as a benefit, a second job, untaxed income or tax owed from a past year.

Can I change my own tax code?

You can’t choose a code, but you can update your details with HMRC online, and HMRC will then issue a new code.

Why is my tax code 0T?

Your allowance is used up elsewhere, or your employer lacked your details when you started. Give them your P45 or starter checklist.

What does K mean in a tax code?

It means the amount HMRC needs to collect is larger than your allowance, so it adds the figure to your taxable pay.

Can I have two tax codes?

Yes. Each job or pension has its own code, and only one of them normally gets your full allowance.

Does my tax code affect National Insurance?

No. National Insurance is worked out separately and depends on your earnings and NI category letter, not your tax code.

Final Verdict: What Is My Tax Code in 2026/27?

If you’re asking “what is my tax code?”, the fastest answer is in the HMRC app or your personal tax account. For most people it is 1257L. Read each part of it, run the five-question check, and update your details with HMRC as soon as something doesn’t fit.