Skip to main content
Part of Start a new job: step by step

Tax codes

Skip contents

If you think your tax code is wrong

Usually, HM Revenue and Customs (HMRC) update your tax code using information they get from your employer or pension provider.

If your tax code is wrong, it’s usually because HMRC has incorrect or missing information.

To correct your tax code, check and update the details HMRC has about you.

Update your details

Using the online service is the quickest way to check and update your details.

  1. Sign in to the Check your Income Tax online service.

  2. Check your employment, pension, estimated taxable income, company benefit and expenses details.

  3. Update your details if there’s anything wrong or missing.

  4. Claim tax relief on your employment expenses - if you have any.

If you’ve left a job and did not get a P45 from your previous employer, ask them for one. This can help to update your details.

What happens next

If your tax code needs to change, HMRC will:

  • update your tax code
  • tell you and your employer the new tax code within 15 working days

After you’ve got your new tax code, if you’re paid: 

  •  monthly - it should be on your next or the following payslip
  •  weekly - it should be on your third payslip

If your payslip does not show your new tax code, speak to your employer to check they’ve got it.

If you’ve paid the wrong amount of tax, you can get a tax refund or pay the tax you owe.

If you cannot use the online service

If you think your tax code is wrong and you cannot use the online service, you can contact HMRC.

If you’ve started a new job, you should wait 35 days for HMRC to get your new income details before contacting them.

If you’re contacting HMRC on someone else’s behalf

If you want to help friends or family with their tax you can register as a ‘trusted helper’.

If you’re an agent and you need to tell HMRC about a change in your client’s income fill in a PAYE Coding Notice query form.

View a printable version of the whole guide

This page is Part of Start a new job: step by step

  1. Step 1 Get your National Insurance number

    You'll usually need your National Insurance number when you start your new job.

    1. Find your National Insurance number
    1. Apply for a National Insurance number if you do not already have one

  2. Step 2 Accept the job offer

    The offer might be ‘conditional’ or ‘provisional’, which means you may need to give further details to your new employer or pass pre-employment checks.

    1. Find out about your rights when accepting a job offer

  3. Step 3 Share your details for any employer checks

    Give your new employer what they need to complete any pre-employment checks.

    1. Find out what checks your employer can make
    1. Find out how to prove your right to work
    1. Find out about criminal record checks

  4. Step 4 Review your employment contract

    Your new employer should give you an employment contract. Check the terms before you agree to it.

    1. Find out about employment contracts

  5. and If you're leaving a job, hand in your notice

    Tell your current employer that you’re going to leave and when your last day will be. This is known as handing in your notice.

    1. Find out how to hand in your notice

    When you hand in your notice, ask your employer when you’ll get your P45.

    1. Find out about the P45

  6. Step 5 Prepare your personal information for your first day

    To get paid, you’ll need to give your new employer:

  7. Step 6 Give your P45 to your new employer

    Your new employer will use your P45 to work out how much tax to take from your pay.

    1. Find out about the P45

  8. or If you do not have a P45, fill in the starter checklist

    Use the starter checklist to give your employer details they need to work out your pay and tax.

    1. Fill in the starter checklist

  9. Step 7 Check your first payslip

    Your employer must give you a payslip on or before payday.

    1. Find out what should be on your payslip

    It’s your responsibility to make sure you’re paying the right amount of tax.

    1. Check if the tax on your payslip is correct

    If you think the tax is wrong, your tax code may be incorrect.

    1. You are currently viewing: Find out what to do if you think your tax code is wrong