PAYE Tax Codes Explained: 1257L, BR, K Codes and More (2026/27)

PAYE Tax Codes Explained (2026/27)

Your PAYE tax code is perhaps the single most important number on your payslip, yet most employees pay it no attention. A wrong tax code can cost hundreds — sometimes thousands — of pounds in overpaid tax, or leave you with an unexpected underpayment bill at year end. Understanding your code takes minutes and can have significant financial consequences.

What Is a Tax Code?

A PAYE tax code is an instruction from HMRC to your employer (or pension provider) specifying how much tax to deduct from your pay each period. Employers are legally required to act on updated codes immediately upon notification.

Every code has two parts: a number and one or more letters. The number (multiplied by 10) gives your annual tax-free amount. The letter tells your employer what type of allowance or adjustment applies.

The Standard Code for 2026/27: 1257L

The most common code is 1257L: 1257 × 10 = £12,570 Personal Allowance; L = standard allowance. If your code differs from 1257L, HMRC has made an adjustment — either increasing or decreasing your tax-free amount. Not all adjustments are errors, but all are worth investigating.

Complete Tax Code Guide

L-Suffix Codes (Personal Allowance)

Emergency and Non-Standard Codes

W1 / M1 (Emergency Basis) Any code with /W1, /M1, or X suffix is non-cumulative (emergency basis). Each pay period is treated independently. Applied when:

• Starting a new job without providing a P45
• HMRC cannot confirm year-to-date earnings
• After certain changes of circumstance

W1/M1 often causes overpayment — provide your P45 immediately to correct it.

Scottish Codes (S-prefix) S1257L, SBR, SD0 — Scottish income tax rates apply. If you live in Scotland but your code lacks the S prefix, contact HMRC: you may be on wrong rates.

Welsh Codes (C-prefix) C1257L — Welsh income tax applies. Currently matches English rates, so minimal practical impact until Wales sets different rates.

K Codes: Negative Allowance K codes add income to your gross pay for tax calculation — representing a negative allowance. HMRC uses them when deductions exceed your Personal Allowance.

K200 example: Tax calculated as if you earn your actual salary PLUS £2,000 extra. This happens when:

• A benefit in kind value (expensive company car, high-value medical insurance) exceeds your Personal Allowance
• Underpaid tax from prior years is being collected through PAYE
• Untaxed state benefits need to be collected

Why Your Tax Code Changes

HMRC issues a P2 Notice of Coding whenever your code changes. Common triggers:

How to Check and Correct Your Code

Step 1: Log in to your HMRC Personal Tax Account at gov.uk/personal-tax-account

Step 2: Navigate to "Check your Income Tax." Review all listed:

• Employment sources and salary estimates
• Benefits in kind
• Untaxed income sources
• Prior year underpayments

Step 3: Correct any inaccurate information. HMRC typically updates your code within 2–5 working days.

Step 4: Your employer applies the new code from the next payroll run.

Alternative: Call HMRC on 0300 200 3300 (Monday–Friday, 8am–6pm).

Claiming Back Overpaid Tax

You can also proactively claim tax relief for:

• Work uniforms/protective clothing maintenance: flat £60/year (or actual cost)
• Professional subscriptions: full amount
• Home working: £6/week (£312/year) flat rate
• Business mileage over HMRC rate: 25p/mile above first 10,000

Frequently Asked Questions

Q: I have two jobs — why is my second job taxed at the higher rate? Your Personal Allowance is assigned to your main employment. HMRC codes your second employment BR (all at 20%) or D0 (all at 40%) because the allowance is already used. If both jobs have relatively low incomes, you can ask HMRC to split the allowance between them.

Q: My code says 1257L W1 — what does W1 mean? W1 means your employer is calculating tax on a "Week 1" (non-cumulative) basis, treating each week as if it's the first of the tax year. This commonly happens when starting a new job without a P45. Provide your P45 to your employer immediately to switch to cumulative calculation.

Q: I received a P800 saying I owe tax — do I have to pay it? Yes, if HMRC's calculation is correct. You can query it online or by phone. Genuine underpayments are typically collected via adjusted PAYE codes in the following year (spread over 12 months), or you can pay immediately to avoid continued interest.

Q: What's the difference between the T suffix and L suffix? The T suffix means HMRC wants to review your code annually rather than adjust it automatically — used for complex situations. The L suffix simply means you receive the standard Personal Allowance. Practically, both 1257L and 1257T currently give the same allowance.