Tell HM Revenue and Customs (HMRC) as soon as possible if you’ve made money you need to pay tax on and haven’t told them about it.

This could have happened because you:

  • didn’t realise you needed to tell HMRC about it
  • weren’t sure how to declare it
  • didn’t declare it because you couldn’t pay the tax

If you contact HMRC first, they may consider your case more favourably.

Income Tax

You don’t need to tell HMRC about income you’ve already paid tax on, eg wages.

You should tell HMRC if you earned other taxable income and haven’t declared it in a Self Assessment tax return. This could include income from:

If this income takes you over your Personal Allowance, you’ll pay tax on it.

What you need to do

You can register for Self Assessment to declare any income you haven’t paid tax on from the last 4 years. You’ll need to fill in a separate tax return for each year. You can also contact HMRC if you have questions.

If you’re already registered for Self Assessment but haven’t declared all your income, you can make a correction to your return.

If you’re employed or get a workplace pension, you can tell HMRC if you think you may owe more tax.

Other taxes

You must register for:

You can contact HMRC if you have questions about undeclared income for Corporation Tax, VAT or PAYE.

Overseas income

If you’re resident in the UK, you may need to report foreign income in a Self Assessment tax return.

If you don’t report this, you may have to pay both:

  • the undeclared tax
  • a penalty worth up to double the tax you owe

You can be prosecuted if you give false information about the tax you owe. If you tell HMRC as soon as you can, they may consider your case more favourably.

You may be eligible to tell HMRC about undeclared income through an ‘offshore disclosure facility’ if:

  • you haven’t told them about your foreign income
  • you’re not paying the right amount of tax
  • you’ve previously made an incorrect claim
  • you’re behind with your tax

If you’re not eligible to use an offshore disclosure facility, but still have tax to declare, contact HMRC’s Offshore Co-ordination Unit.

HMRC Offshore Co-ordination Unit
Telephone: 03000 530 310
Monday to Friday, 9am to 4pm
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