How to use this UK tax code explainer
A UK tax code tells your employer or pension provider how much Income Tax to deduct through PAYE. This tool helps you break that code down in simple language, so you can see whether you are getting a normal tax-free allowance, being taxed at a flat rate, or using a special or emergency code.
You can use this page to check common codes including 1257L, BR, 0T, D0, D1, NT, K codes, Scottish tax codes, Welsh tax codes and emergency tax codes.
What a UK tax code is
A tax code is the short code HMRC uses to tell payroll how to tax your salary or pension. Some codes give you a tax-free allowance through that employer or pension. Others tell payroll to tax all income at a set rate, or to use temporary treatment until HMRC has the right information.
Why your tax code matters
If your tax code is wrong, you could pay too much tax or too little tax during the year. A quick check can help you spot issues after starting a new job, taking a second job, beginning a pension, receiving benefits in kind, or noticing your net pay has changed unexpectedly.
What the numbers usually mean
In many standard tax codes, the numbers broadly relate to the amount of tax-free income being given through that job or pension. For example, 1257L is commonly associated with the standard Personal Allowance. The numbers are not a payslip calculation by themselves, but they often show the allowance amount HMRC want payroll to use.
What the letters usually mean
The letters in a tax code help show how payroll should treat the income source. For example, L is the most common standard suffix, while BR, D0 and D1 tell payroll to tax all income from that source at a specific rate. NT means no tax is deducted from that source, and a K code usually means HMRC are effectively adding an amount to taxable pay rather than giving extra tax-free pay.
Common UK tax codes explained
- 1257L usually means the standard Personal Allowance is being applied.
- BR means all income from that source is taxed at the basic rate.
- 0T means no Personal Allowance is being given through that payroll.
- D0 and D1 mean all income from that source is taxed at higher or additional rates.
- K codes mean HMRC are adding an amount to taxable pay rather than giving tax-free pay.
- S and C prefixes mean Scottish or Welsh tax treatment applies.
- W1, M1, X and NONCUM usually indicate emergency or non-cumulative treatment.
When to check your tax code
It is worth checking your code when you start a new job, change jobs, take a second job, start drawing a pension, receive company benefits, or notice your take-home pay has changed. You should also check your code if HMRC send you a coding notice or if a payslip suddenly shows a code you do not recognise.
What this tool does not do
This page is designed to explain the structure and likely meaning of a tax code. It does not replace HMRC’s own coding notices, your Personal Tax Account, or a full PAYE calculation. A code can be technically valid and still be wrong for your circumstances if HMRC are working from incomplete or outdated information.
Important note
This explainer is designed to help you understand common UK tax code formats quickly. It is not a substitute for HMRC’s own coding notices or online tax account. If your code looks wrong, check the official HMRC explanation and contact HMRC if needed.