Understanding Your Tax Code: What It Means & How to Check It

Tax Guides · 8 min read · Updated 2026-03-22

Learn how UK tax codes work, what the letters and numbers mean, how to check your tax code is correct, and what to do if HMRC has given you the wrong code.

Written by Krishna, Founder & HMRC-registered tax agent at TaxRoot.

What does 1257L mean on my tax code?

The number 1257 represents your personal allowance of £12,570 (the last digit is removed). The letter L means you are entitled to the standard tax-free personal allowance. This is the most common tax code and means your employer will not deduct tax on the first £12,570 of your annual earnings.

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