UK Tax Codes Explained: 1257L, BR, and Emergency Taxes
Is your tax code correct? A wrong letter or number on your payslip could mean you are overpaying HMRC by thousands of pounds a year.
Your tax code is a small string of numbers and letters on your payslip that dictates exactly how much money HMRC takes from your gross salary. Despite its importance, millions of UK workers never check their tax code, assuming their employer or the government always gets it right. Unfortunately, administrative errors are common, and being on the wrong code is the number one reason people overpay tax.
The Standard Code: 1257L
For the vast majority of employees with one job in the 2025/26 tax year, your code should be 1257L.
- 1257: This number represents your Personal Allowance. Multiply it by 10 to get the amount you can earn tax-free (£12,570).
- L: This letter indicates you are entitled to the standard tax-free Personal Allowance.
If your code is 1257L, your employer takes your annual salary, subtracts £12,570, and only taxes the remainder. This is exactly how our Take-home Pay Calculator runs its base calculations.
The Dreaded "Emergency" Tax Codes: W1, M1, or X
If your tax code ends in 'W1', 'M1', or 'X' (e.g., 1257L W1), you are on an emergency tax code. This usually happens when you start a new job and your new employer doesn't have your P45 from your previous job. Under an emergency code, your tax is calculated strictly on your earnings for that specific pay period (Week 1 or Month 1), without taking into account the tax you've already paid earlier in the year. This often results in you paying too much tax. You need to provide your employer with your P45 or a New Starter Checklist to fix this.
The "Second Job" Codes: BR, D0, D1
You only get one Personal Allowance. If you have a second job or a side hustle paid via PAYE, that second income source cannot use the £12,570 tax-free buffer.
- BR (Basic Rate): All income from this job is taxed at a flat 20%. No tax-free allowance is applied.
- D0: All income is taxed at the Higher Rate of 40%.
- D1: All income is taxed at the Additional Rate of 45%.
The "Penalty" Code: K
A tax code starting with a 'K' (e.g., K497) means you owe HMRC money, or you are receiving taxable company benefits (like a company car or health insurance) that exceed your Personal Allowance. The number after the K indicates how much must be added to your taxable income to recover the owed tax. It essentially works as a negative personal allowance.
How to Claim Tax Back
If you discover you've been on the wrong tax code (like BR on your main job), don't panic. HMRC allows you to claim back overpaid tax for up to the last four tax years. You can usually resolve this by logging into your Personal Tax Account on the Gov.uk website or calling HMRC directly. Once corrected, they will issue a refund either via a tax code adjustment or a direct cheque.