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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.
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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.
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:
If for some reason you don't have a P45, you will complete a P46 with your employer who 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 P46 to HMRC so they can set up a record for you and review your tax code. You must not send the P46 to HMRC yourself. 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.
You should wait at least 28 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 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:
If you can't find any record of your tax reference and National Insurance number, HMRC will tell you what to do.