What to do if your tax code is wrong

If you think your tax code is wrong you need to tell HM Revenue & Customs (HMRC) as soon as possible to make sure you pay the right amount of tax. If it is wrong you may be due a tax refund, or need to pay more tax.

On this page:

Why your tax code is important

HMRC issues your tax code based on information they have about your taxable income and allowances: it tells your employer or pension provider how much Income Tax to deduct from your wages or pension. Read the related guide below to help you understand your tax code.

Tax codes - the basics


If you're on an emergency tax code

When you start a new job you should give your new employer a form P45, if you have one from your last job. This shows:

  • your tax code
  • your previous earnings
  • how much tax you have paid

If for some reason you don't have a P45, your new employer may give you a Starter Checklist to complete, or ask you relevant information before your first payday to tell HMRC about you. This will help your employer allocate a tax code and work the tax due on your first payday. HMRC will process the information you have provided on the Starter Checklist and where necessary, revise the tax code. It’s important that you complete the Starter Checklist or provide the relevant information your employer has asked as soon as possible before your first payday, so your employer knows what tax code to use. If you don’t you could end up paying the wrong amount of tax. You can also complete and print a copy of the Starter Checklist by following the link below. Give it to your employer; do not send the checklist to HMRC.

Starter Checklist

If you delay in providing your employer with the relevant information, your new employer will then use an 'emergency' or 'special basis' tax code. While you're on an emergency code you'll get the basic Personal Allowance - this may or may not be right for you. Your employer will send the information you’ve provided to HMRC so they can set up a record for you and review your tax code. Once HMRC has details of your previous income and tax paid for the tax year, they send your employer (and you) your full (correct) tax code. Your employer will deduct the correct tax in future and refund any overpaid tax.

Read more about emergency tax codes

Find out about tax refunds and reclaiming overpaid tax

Contacting HMRC

You should wait at least 35 days before contacting HMRC where you have recently started a new job or pension as your new employer or pension provider will notify them automatically.


If your tax code is wrong

If your tax code is wrong you need to contact HMRC so they can correct it.

HMRC will need to know your tax reference and National Insurance number. Look for these numbers on official papers to do with tax, for example:

  • a payslip
  • letters from HMRC
  • a certificate of tax paid
  • a 'PAYE Coding Notice' if you have one - this is a notice telling you what your tax code is. HMRC usually sends it out in January or February each year and they may also send it to you at other times - for example, if you've started receiving a new source of income or a new company benefit, or if your entitlement to age-related or other allowances has changed (Not everyone gets one of these)

If you can't find any record of your tax reference and National Insurance number, HMRC will tell you what to do.

Contact HMRC

New online form to tell HMRC your tax code is wrong

You can use the new HMRC email service to let them know that your tax code is wrong.

Tell HMRC that your tax code is wrong


More useful links

Working and paying tax