How to Check and Correct Your UK Tax Code Using HMRC: Step-by-Step Guide

How to check and correct your UK tax code in 2026/27

A wrong PAYE tax code can mean too much Income Tax is deducted from your wages or pension—or too little, leaving a bill later. The most reliable approach is to compare your payslip with HMRC’s own record, correct the underlying information, and check a later payslip. This guide follows HMRC’s published procedures for the tax year 6 April 2026 to 5 April 2027.

This is a practical guide for employees and pension recipients paid through PAYE in England, Scotland, Wales and Northern Ireland. Tax bands can differ by nation; the code prefix matters. It is not a guide to filing a Self Assessment return, and a tax code alone cannot tell you your final annual tax liability.

Quick diagnosis: what exactly looks wrong?

Before you begin: collect the right information

• Your latest payslip, showing tax code, gross pay, tax deducted and pay period.
• Your National Insurance number and HMRC sign-in details; you may need to prove your identity.
• Your P45 if you recently changed jobs, plus any P60 or pension information relevant to the issue.
• Details of every current job and taxable pension, estimated annual pay and benefits in kind.
• Any recent HMRC tax-code notice and information about taxable benefits, reliefs or underpaid tax.

Never send your National Insurance number, login codes, payslips or passport images to an unofficial “tax code checker”. Start from GOV.UK’s current-year Income Tax service, not an advertisement or unsolicited message.

Step-by-step: check your tax code using HMRC

Step 1 — Find the tax code on your payslip

Look for a code such as 1257L, 1257L M1, BR or S1257L. Write it down exactly, including any prefix or suffix. Your employer uses the code in PAYE payroll calculations, but HMRC decides which code to issue. A separate code may apply to each job or pension.

Step 2 — Sign in to the official Check your Income Tax service

Open Check your Income Tax for the current year and sign in. You can also use the official HMRC app. The service shows your tax code, Personal Allowance, estimated income, jobs and pensions, and changes reported to HMRC. The current year runs from 6 April 2026 through 5 April 2027. People who pay Income Tax only through Self Assessment cannot use this particular current-year service.

Step 3 — Compare the code in HMRC with your payslip

If the two codes differ, contact your employer or pension payroll team and ask whether it has received and applied the latest HMRC notice. Do not ask payroll to invent a different code; it normally must use the one HMRC has instructed it to use. If both codes match but the deductions look wrong, investigate the inputs and calculation instead.

Step 4 — Review the income and employment details HMRC holds

Look at every listed employment and pension, your estimated taxable income, company benefits, expenses and allowances. A former job still shown as active, an unexpectedly high estimate or an unreported taxable benefit can affect your code. Check carefully before editing: some amounts may be correct estimates even when different from one month’s payslip.

Step 5 — Update incorrect or missing information

Follow the online service’s update options for employment, pensions, estimated taxable income, company benefits or expenses. If you left a job without receiving a P45, ask the previous employer for it. Where applicable, submit a claim for employment-expense tax relief through the appropriate HMRC route. Keep confirmation of the change and do not submit repeated contradictory updates.

Step 6 — Wait for HMRC to issue a revised code

HMRC says it will tell you and your employer the revised code within 15 working days when a change is needed. For monthly pay, the revised code should normally appear on your next or following payslip; for weekly pay, by your third payslip. If it does not, ask payroll whether the code notice has been received and applied. These are official typical timeframes, not a guarantee for every unusual case.

Step 7 — Check the result and any refund or underpayment

Compare the new code and tax deduction with your next payslip. If you overpaid and HMRC has complete income information, a refund may be made through payroll after the updated code is applied. If you underpaid, HMRC may collect the difference through an adjusted code or another formal process. Do not assume a lower tax deduction means the entire issue is resolved.

How to read common UK tax codes

For 2026/27, the standard Personal Allowance is £12,570, and 1257L remains the common standard code. But it can be changed by benefits, other untaxed income, tax owed, reliefs or the income level at which Personal Allowance is reduced. Do not treat 1257L as a universal target. Use HMRC’s official code explanations for your actual code.

Emergency tax code after starting a new job

Codes ending W1, M1 or X use the current pay period rather than calculating PAYE cumulatively across the tax year. This can temporarily produce an unexpected deduction, particularly if you have changed jobs, started part-way through the year or received a large payment. HMRC says the new employer’s first payroll report and any P45 details help it establish the correct code.

• Give your new employer the P45 from your previous employer if you have one.
• If you have no P45, complete the new-starter information requested by your employer accurately.
• Check that the old employment is no longer incorrectly treated as current.
• HMRC advises people who have just started a job to allow 35 days before contacting it about a possibly incorrect new-job tax code.
• If the code still looks wrong after that period, review and update your details online or contact HMRC.

Important nuance: 1257L without W1, M1 or X is not itself an emergency code. A payroll code ending in M1 does not mean Marriage Allowance: here M1 indicates month-one non-cumulative treatment. See HMRC’s emergency-code guidance.

Why a code can change even when you did not change jobs

A PAYE code can be adjusted for a company car, employer-provided medical insurance, untaxed savings interest, State Pension, another pension, tax owed from a previous period, eligible expenses or Marriage Allowance. A change in your estimated annual income can also alter the Personal Allowance available to you. HMRC’s official explanation of code changes lists these situations. Rather than trying to “restore” an old code, identify the underlying item and correct it if inaccurate.

Multiple jobs or pensions: avoid a common mistake

You may have one code for your main employment and another for a second job or pension. A BR code on the second source is not automatically an error, and asking for the standard allowance on every source could cause an underpayment. Check all income sources together in HMRC’s account and verify which one uses the Personal Allowance. The correct allocation depends on your complete circumstances.

Scotland, Wales and the rest of the UK

A code beginning with S generally signals Scottish Income Tax treatment, while C indicates Welsh treatment. Rates and bands can differ, so two people with the same salary may have different PAYE deductions. If the prefix appears inconsistent with where you live for tax purposes, check the address and residence information HMRC holds; do not simply remove the prefix from your payslip.

Your payslip is different from HMRC: what to do

First confirm that you are comparing the same job, same tax year and latest payslip. If HMRC’s code is newer, payroll may not have processed it yet. Ask payroll to check the notice received from HMRC. If the codes match but the deduction differs from your expectation, compare gross pay, taxable benefits, bonus payments, cumulative pay, National Insurance and pension deductions; those are not all the same as Income Tax. HMRC publishes a payslip tax-checking guide with an official estimate tool.

If you cannot sign in or verify your identity

• Start from the official GOV.UK current-year service or HMRC app, rather than following a link in a text message.
• Check whether you are using the correct sign-in credentials and can access the required verification method.
• If prompted to prove identity, follow the exact official on-screen instructions; requirements vary by user.
• If you cannot create a personal tax account or complete online access, use the official Income Tax contact page.
• If Self Assessment is your only Income Tax route, use the appropriate Self Assessment service instead of assuming the PAYE current-year tool is broken.

How refunds and underpayments are handled

When HMRC has enough information, it may adjust the code and arrange for an overpayment to be refunded through your employer or pension provider. If it lacks information, the refund may need to wait until the employer or provider reports it. After the tax year, HMRC may reconcile records and contact you about tax paid incorrectly. An underpayment can result in a changed code or an amount due. Always check the notice rather than guessing what a tax-code change means. Read HMRC’s overpayment and underpayment guidance.

Troubleshooting checklist

A practical worked example

Suppose your payslip shows BR for your only job, but you have no other employment or pension. Do not assume BR is definitely wrong: HMRC may have information you have overlooked. Sign in to the current-year service, check whether an old job remains active, review the income estimates and update any incorrect records. If HMRC changes your code, wait for the revised payroll instruction and compare a later payslip. This example illustrates the process; it is not a personal tax calculation.

What to do if the problem is not resolved

If the online information is accurate but your code still appears inconsistent, contact HMRC using its official Income Tax enquiries page. Have your code, recent payslips, employment dates and any HMRC notices ready. For an urgent pay discrepancy, also ask your payroll team to check the code it has applied. Complex tax affairs, multiple income streams or disputes about earlier years may warrant advice from a qualified UK tax professional.

Official sources and verification

Check your Income Tax for the current year — HM Revenue & Customs / GOV.UK

Tax codes: overview — HM Revenue & Customs / GOV.UK

What your tax code means — HM Revenue & Customs / GOV.UK

How to update an incorrect tax code — HM Revenue & Customs / GOV.UK

Emergency tax codes — HM Revenue & Customs / GOV.UK

Check if the tax on your payslip is correct — HM Revenue & Customs / GOV.UK

Overpaid or underpaid tax — HM Revenue & Customs / GOV.UK

2026/27 tax codes and Personal Allowance — HM Revenue & Customs / GOV.UK

Editorial verification: 16 October 2026. This is general information, not personalised tax advice. Check current HMRC guidance when acting, as service screens and tax rules may change.