Tax code
What it really means
A short code like 1257L on your payslip that tells your employer how much tax-free income you get before tax starts. A wrong code can mean you pay too much or too little tax. You can check it in your Personal Tax Account on GOV.UK.
Context, tips & common mistakes
Your first UK job is the classic moment for a wrong code: with no P45 to hand over, payroll puts you on an emergency code and more tax comes off than necessary. This is normal and self-correcting — once HMRC processes your details the code updates and overpaid tax usually comes back automatically through a later payslip or an end-of-year calculation — but it corrects faster if you complete the starter checklist your employer gives you accurately. Check your code in the free personal tax account on GOV.UK rather than guessing; the account shows how the number is built from your tax-free allowance. Watch out after changing jobs mid-year or holding two jobs at once, when codes most often go wrong, and be sceptical of 'tax refund agents' advertising online — they claim refunds you could get yourself for free, and take a large cut. HMRC never texts links demanding bank details for a refund; those messages are scams.