Tax Code Checker — What Does Your Tax Code Mean?
Your tax code tells your employer how much income tax to deduct from your pay. Get it wrong, and you could be overpaying — or underpaying — tax every single month without realising it. HMRC estimates that roughly 1 in 10 tax codes contain errors.
This tool decodes your HMRC tax code into plain English. Enter the code from your payslip, P45, P60 or HMRC coding notice and it will explain exactly what it means — your tax-free allowance, the letter suffix, and whether anything looks unusual.
How to use: Type your tax code into the box below. The most common code is 1257L — if yours is different, the tool will explain why and flag anything worth checking with HMRC.
How UK tax codes work
A UK tax code is HMRC's instruction to your employer about how much income tax to deduct from your pay each month. The code is made up of a number and a letter. The number represents your tax-free allowance — multiply it by 10 to get the annual amount. So a code of 1257 means a £12,570 tax-free allowance. The letter indicates your circumstances.
The most common code is 1257L, which applies to most employees with one job and no complications. The L suffix means you are entitled to the standard personal allowance. If your code is different, it means HMRC has adjusted your allowance — sometimes correctly (for example, if you have a company car), and sometimes in error.
Your tax code can change during the year if your circumstances change. HMRC will send you a coding notice (form P2) explaining any changes. Always check this against your payslip to make sure the right code has been applied.
Frequently asked questions
Where do I find my tax code?
Your tax code appears on your payslip (usually near the top), your P45 (when you leave a job), your P60 (annual summary from your employer), and your HMRC coding notice (form P2). You can also find it by logging into your personal tax account on the HMRC website or app.
What is an emergency tax code?
Emergency tax codes (such as 0T, BR, or codes ending in W1 or M1) are applied when HMRC does not have enough information about you — typically when starting a new job without a P45. They usually result in overpaying tax. Once HMRC receives the right information, they will issue a corrected code and your employer will adjust your pay. If an emergency code stays on your payslip for more than two months, contact HMRC directly.
What does a K code mean?
A K code means you have untaxed income that exceeds your personal allowance. Common causes include a company car, private medical insurance, or tax owed from a previous year. HMRC collects the extra tax through your PAYE by effectively adding to your taxable income rather than reducing it. The number after the K tells you the amount — multiply by 10 to see the annual figure.
Can I have different tax codes for different jobs?
Yes. If you have more than one job, your personal allowance is usually allocated to your main job (code 1257L or similar). Your second job typically gets a BR code (basic rate — all income taxed at 20%) since your allowance is already used. You can ask HMRC to split your allowance between jobs if you prefer.
How do I get a wrong tax code corrected?
Contact HMRC directly on 0300 200 3300 or through your personal tax account online. They can update your code, and your employer will receive the corrected code automatically. If you have been overpaying tax due to a wrong code, HMRC will issue a refund — either through an adjusted code for the rest of the year or as a cheque/bank transfer after the tax year ends.
Related tools
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Book a free discovery callTax codes are issued by HMRC and can change during the tax year. This tool provides general guidance on what codes mean based on standard HMRC conventions. Your actual tax position may differ depending on individual circumstances. Grosvenor Solutions is a trading name of Imperial Consulting Limited.