Your tax code is the instruction HMRC sends to your employer or pension provider so they can work out how much Income Tax to take under PAYE. If the code is wrong, you can pay too much tax or too little tax during the year.
What does a UK tax code mean?
A tax code usually combines numbers and letters. The numbers normally show how much tax-free income you can get in a year, divided by 10. The letters give extra information about your circumstances.
For many employees, the standard code in 2026/27 is 1257L. That usually means you are getting the full £12,570 Personal Allowance through one job or pension.
1257L usually means the standard Personal Allowance of £12,570.
The number 1257 broadly points to £12,570 of tax-free pay.
The letter L usually means you are entitled to the standard Personal Allowance.
Your code can be different and still be correct.
How do I read my tax code letters and numbers?
Start with the number, then the letter, then any prefix or suffix. The number is the easiest part to read. The letter or extra symbol tells you why the code is standard, reduced, shared or taxed in a special way.
What the numbers usually mean
If your code is 1257L, HMRC is usually giving you £12,570 of tax-free income. If the number is lower, HMRC may have reduced your allowance for something like benefits in kind, unpaid tax from an earlier year, or because some allowance is being used elsewhere.
If the number is higher, you may have had extra allowance added. That can happen in some cases if HMRC is adjusting for earlier overpayments or giving relief through your code.
What common tax code letters and markers mean
L: you usually get the standard Personal Allowance.
M: you have received part of your spouse's or civil partner's Marriage Allowance.
N: you have transferred part of your Personal Allowance to your spouse or civil partner under Marriage Allowance.
K: deductions are larger than your allowances, so extra taxable income is added to your pay for tax purposes.
BR: all income from that job or pension is taxed at the basic rate.
D0: all income from that job or pension is taxed at the higher rate.
D1: all income from that job or pension is taxed at the additional rate.
0T: no Personal Allowance is being given in that employment, often because HMRC needs more information.
W1 or M1: the code is being operated on a week 1 or month 1 basis, so each pay period is treated on its own.
X: sometimes used instead of W1 or M1 to show a non-cumulative basis.
What is the standard tax code in 2026/27?
The standard tax code for many people in 2026/27 is 1257L. That reflects the £12,570 Personal Allowance. But it is only standard if you qualify for the full allowance and use it against one main source of PAYE income.
A different code does not automatically mean something is wrong. If you have a company benefit, more than one job, a pension, Marriage Allowance, or tax owed from an earlier year, a non-standard code can be expected.
Why has my tax code changed?
Tax codes change when HMRC receives new information about your pay or circumstances. That information can come from your employer, pension provider, you, or HMRC's own records.
You started a new job and HMRC did not yet have full pay details.
You now have more than one job or pension.
You began receiving company benefits, such as private medical cover or a company car.
You claimed or transferred Marriage Allowance.
HMRC is collecting underpaid tax from an earlier year through your code.
You stopped working, changed hours or moved to a different salary.
You went above £100,000, where the Personal Allowance starts to reduce.
Your employer used an emergency or temporary code while waiting for the right one.
How do I know if my tax code is wrong?
The clearest sign is that your code does not match your situation. If you have one job and no obvious adjustments, a simple code like 1257L is common. If you see BR, D0, D1, 0T or a K code, it is worth checking why.
Another sign is a sudden change in take-home pay that you were not expecting. A new tax code can increase or reduce PAYE tax straight away, especially if the code is cumulative rather than week 1 or month 1.
Your tax code changed and you were not told why.
You changed jobs recently and are still on an emergency-style code such as 0T, W1 or M1.
You have one job but all of the pay is being taxed at BR, D0 or D1.
Your payslip tax looks high or low compared with your gross pay.
Your code includes benefits or adjustments that no longer apply.
Your Personal Allowance may have reduced because income is above £100,000, but your code does not seem to reflect that.
How can I check if my tax code is right?
Check three things: your payslip, the tax code notice from HMRC, and your actual circumstances. The code on your payslip should match the latest code HMRC has issued, unless your employer has not applied the update yet.
Look at your current payslip and note the tax code being used.
Read any HMRC tax code notice and check the adjustments listed.
Check whether you have one job, more than one job, a pension, benefits in kind, or Marriage Allowance.
Check whether you changed jobs during the year and whether a temporary code was used.
If your income is above £100,000, check whether your Personal Allowance may be tapering away.
Compare your tax deducted with your expected take-home using a salary calculator.
If you want to sense-check the effect on your pay, run your salary through a take-home calculator and compare it with your payslip. That will not confirm the code itself, but it can show whether the tax being deducted looks broadly in line with your pay and deductions.
Where do I find my tax code?
You can usually find your tax code on your payslip, your P45 or P60, letters from HMRC, or in your HMRC online account. If you have more than one job or pension, you may have more than one tax code at the same time.
That matters because HMRC often gives your Personal Allowance to one main income source and taxes the others differently. So seeing BR or 0T on a second job is not automatically an error if your main job uses your allowance.
What should I do if my tax code is wrong?
If the code looks wrong, contact HMRC and ask them to review it. Your employer usually cannot choose your tax code unless they are applying a starter or emergency code based on the information you gave them.
When you speak to HMRC, have your employer details, estimated annual pay, benefits information, and details of any other jobs or pensions ready. If HMRC changes the code, your employer will normally apply the new code through payroll.
If you have overpaid tax, the correction may happen through later payslips or after the tax year is reconciled. If you have underpaid tax, HMRC may collect it through a revised code or by another process depending on the amount and the timing.
Do emergency tax codes fix themselves?
Sometimes, yes. Emergency or temporary codes often appear when you start a new job and payroll does not yet have your full tax history. Once HMRC and your employer receive the right information, the code can be updated automatically.
But not always. If a temporary code stays in place for more than a few pay periods, or your tax still looks unusual, it is worth checking your HMRC records and payslips rather than assuming it will sort itself out.
How does a tax code affect take-home pay?
Your tax code changes how much of your pay is taxed before PAYE is deducted. A lower allowance in your code usually means more tax is taken during the year. A higher allowance usually means less tax is taken.
National Insurance is separate from your tax code. In 2026/27, employees pay 8% on earnings between £12,570 and £50,270, and 2% above £50,270. So a tax code error affects Income Tax, but not the NI rates themselves.
If you also repay a student loan or make pension contributions, your overall take-home can move for several reasons at once. That is why it helps to check your full payslip rather than only the tax line.
What is a simple way to sense-check my tax code?
Use a simple rule of thumb. If you have one job, no benefits, no other PAYE income, and your income is not high enough to reduce your allowance, a straightforward code is common. If your code is more complex, there should usually be a clear reason for it.
The key point is not whether your code looks normal compared with someone else's. It is whether it matches your own pay, benefits and HMRC record. A code that is unusual for one person can be completely right for another.