By Tax Calculator UK · Published · 7 min read
How to find your tax code
Your tax code is printed on your payslip, your P60 and any tax code notice from HMRC. You can also see it, with an explanation of how it was worked out, in your HMRC online account or the HMRC app. Our payslip guide shows where to look.
What should my tax code be?
If you have one job or pension, no taxable benefits and no tax owed from earlier years, your code should be 1257L for 2026/27 (S1257L in Scotland, C1257L in Wales). That gives the full £12,570 Personal Allowance. Read more in tax code 1257L explained.
Anything different should have a reason you can match to your own situation. The table lists the usual ones.
Common reasons your tax code changed
| Change | What usually happens to your code |
|---|---|
| You started getting a company car or medical cover | Number goes down, or becomes a K code |
| You started a second job | Second job goes on BR, D0 or D1 |
| You owe tax from an earlier year | Number goes down to collect it over the year |
| You claimed Marriage Allowance | Ends in M (receiving) or N (giving) |
| You claimed work expenses or pension relief | Number goes up |
| You earn over £100,000 | Number goes down as allowance tapers |
| You moved to or from Scotland or Wales | S or C prefix added or removed |
| You started a new job without a P45 | Emergency code such as 1257L M1 |
How to change your tax code
Only HMRC can change your tax code. Your employer can't. Update your income, benefits or expenses in your HMRC online account or the app, or contact HMRC by phone. HMRC then sends the new code to your employer, who applies it from the next payroll.
If you've been on a wrong code, overpaid tax is normally returned through your pay, and underpaid tax is usually collected through next year's code. If you've just started a job, our guide to emergency tax codes covers what to expect.
Check what a code means for your pay
Enter your code and salary in the tax code calculator to see the tax per year and per month, then compare with your payslip. For a full take-home figure including National Insurance, see the £28,000, £32,000 or £40,000 after tax pages.
Find the changed assumption
Compare the explanation behind the old and new code, not just their numbers. A changed income estimate or benefit entry is a more useful starting point for a query than the net-pay difference alone.
Frequently asked questions
Why has my tax code changed?
Usually because HMRC has new information: a taxable benefit, a second job, tax owed from an earlier year, Marriage Allowance, expenses or a change in income.
Check it on GOV.UK: Tax codes (opens GOV.UK in a new tab)
What tax code should I be on?
Most people with one job and no benefits should be on 1257L for 2026/27, or S1257L in Scotland and C1257L in Wales.
Check it on GOV.UK: Tax codes (opens GOV.UK in a new tab)
Why has my tax code changed from 1257L to a lower number?
The number is your tax-free allowance divided by 10. A drop from 1257L to 1231L, for example, cuts your allowance by £260, which costs £52 a year at 20%. Common causes are a taxable benefit or a small underpayment from an earlier year being collected.
Check it on GOV.UK: Tax codes (opens GOV.UK in a new tab)
Why has my tax code changed on my pension?
If you get the State Pension as well as a private pension, HMRC reduces the allowance on your private pension to cover the State Pension, which is paid without tax taken off. A State Pension increase each April usually lowers the code a little.
Check it on GOV.UK: Tax on your private pension (opens GOV.UK in a new tab) · Tax codes (opens GOV.UK in a new tab)
Why has my tax code changed when nothing has changed?
HMRC may have updated an estimate of your income, received new information from your employer, or started collecting tax owed from a previous year. Your HMRC online account shows how the new code was worked out.
Check it on GOV.UK: Tax codes (opens GOV.UK in a new tab)
Can my employer change my tax code?
No. Only HMRC issues tax codes. Your employer applies the code HMRC sends.
Check it on GOV.UK: Tax codes (opens GOV.UK in a new tab)
How do I check my tax code?
Look at your payslip or P60, or sign in to your HMRC online account or the HMRC app to see your code and how it was calculated.
Check it on GOV.UK: Tax codes (opens GOV.UK in a new tab)