Archive Website of the UK government

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.

• Tax codes - the basics

If your tax code is wrong

If your tax code is wrong, you need to contact HMRC straight away 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 the PAYE Coding Notice out in January or February each year. 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 Opens new window

Your Tax Office 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, a PAYE Coding Notice, letters from HMRC, or a certificate of tax paid.

If you can't find any record of the numbers, your Tax Office will tell you what to do.

Emergency tax codes

Income Tax rates and allowances

Check up-to-date figures for personal allowances from HM Revenue & Customs

• Income Tax rates and allowances Opens new window

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 employer will ask you to complete a form P46 and use an 'emergency' or 'special basis' code. While you're on an emergency code you'll get the basic Personal Allowance - this may or may not be right for you.

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. That’s why it’s very important that you give HMRC any information they ask you for.

• Read more about emergency tax codes

• Find out about tax refunds and claiming overpaid tax

More useful links

• More information on working and paying tax

Useful contacts

• Money, tax and benefits contacts

• National Insurance Contributions Office