Guide
UK Tax Codes Explained: Letters and Numbers
Read the whole code: the allowance or rate, any Scottish or Welsh prefix, and the way payroll applies it during the year.
Quick answer
1257L commonly gives the standard allowance. 0T gives no allowance, BR and D0 apply flat rates, and W1/M1/X/NONCUM limits the calculation to the current pay period. Your circumstances determine which code is appropriate.
On this page
Common UK tax codes at a glance
These rates describe England and Northern Ireland for 2026/27; the Welsh rates currently match. Scottish prefixes need their own interpretation.
| Code | What it does |
|---|---|
| 1257L | Standard £12,570 allowance. |
| 0T | No allowance; ordinary tax bands still apply. |
| BR | All pay from this source taxed at 20%. |
| D0 | All pay from this source taxed at 40%. |
| D1 | All pay from this source taxed at 45%. |
| K | Adds an amount to taxable pay instead of giving an allowance. |
| NT | No Income Tax on this source. |
| M / N | Marriage Allowance received / transferred. |
| T | Other allowance calculations. |
Move to the specific code you can see
If your payslip or HMRC notice shows a concrete code, these pages are more useful than a general overview because they focus on the deduction pattern you should expect.
What should my tax code be?
Salary alone cannot answer this. HMRC also needs your other income, allowances, benefits and any adjustments. A second job does not automatically require a particular flat-rate code; check how your allowance and rates have been allocated across all PAYE sources.
Use HMRC’s current-year Income Tax service to view the code for each employment and check the details behind it. Our step-by-step tax-code check helps you decide whether the next question belongs with payroll or HMRC.
What does the number in a tax code mean?
For an ordinary numbered allowance code, multiplying the number by ten gives a useful guide to the annual tax-free amount. It is not the rule for every code: BR, 0T and NT work differently, and K adds to taxable pay.
The standard Personal Allowance is £12,570 in 2026/27. It can be reduced by taxable benefits or other adjustments; adjusted net income above £100,000 also reduces it. A lower number is therefore not automatically wrong. Read the individual breakdown in your HMRC account or coding notice.
Is 1257L an emergency tax code?
1257L alone is not an emergency code. Look for W1, M1, X or NONCUM. These markers mean the calculation uses that pay period without reconciling earlier periods in the tax year. They can appear after a job change while previous pay information is being obtained, or for other in-year adjustments.
A cumulative calculation instead considers pay and tax so far in the year. Read the cumulative versus M1/W1 guide if the same gross pay produced a different deduction after a code change. Neither an emergency marker nor BR alone establishes that you have overpaid.
Scottish S and Welsh C prefixes
S directs payroll to Scottish rates; C identifies Welsh rates. For example, S1257L uses Scottish bands, while C1257L uses Welsh bands. Crucially, SD0 is the Scottish intermediate-rate code, not the same rate as D0.
Use the Scottish tax-code guide or the official code lookup for the full list. Check HMRC’s address record if the prefix does not match your circumstances.
How can I check what changed on my payslip?
Compare the code, tax basis, taxable pay and tax paid to date with the previous payslip. National Insurance, student loans and pension contributions are separate deductions, so lower take-home pay is not necessarily caused by an Income Tax code change.
The payslip checker helps investigate the figures you provide. It does not access your HMRC records or decide which allowances you are entitled to. If the underlying code details appear wrong, follow the correction checklist rather than choosing a replacement code yourself.
What to check
- Read 0T as zero-T: it means no allowance, not no tax.
- Include the S or C prefix and any emergency marker when comparing codes.
- Check each job or pension separately in your HMRC account.
What to do next
- Choose the matching code guide below for a worked explanation.
- Use HMRC’s current-year service to check the records behind your code.
- Investigate an unexpected payslip deduction without assuming the code alone proves an error.
Try the tool
Check your payslip or model a change.
Use the checker if you already have a payslip. Use the calculator if you want to model take-home pay or salary-sacrifice changes before payday.
About this guide
Published by IsMyPayRight to help you understand pay and deductions. Guides use official reference material and practical examples, with AI assistance in content preparation.
This is general guidance, not a professional review of your circumstances. Read our editorial process and corrections information.
Methodology and sources
See how the calculations work, which sources they use, how results are tested, and which payroll details the estimates cannot verify.
Common questions
- What do the letters in a tax code mean?
- The letters show the broad treatment of the allowance or rate. For example, L usually means the standard allowance, BR means basic-rate tax on all pay, and D0 means higher-rate tax on all pay.
- Is 1257L the normal tax code in the UK?
- 1257L is the standard code for many employees with the full personal allowance and no special adjustments, but it is not the right code for everyone.
- Why can a tax code change in the middle of the year?
- HMRC can change a code after a new job, a benefit-in-kind update, an underpayment adjustment, or new information about your total income.
Official sources
Official sources
Use these references to check the rules behind this guide. Check the tax year and your circumstances before applying an example to your own pay.