If you have not told HMRC about Income

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

This could have happened because you:

did not realise you needed to tell HMRC about it
were not sure how to declare it
did not declare it because you could not pay the tax

If you contact HMRC first (external link), they may consider your case more favourably.

Income Tax

You do not need to tell HMRC about income you have already paid tax on, for example wages. But if you do not think enough tax has been taken on your employment or workplace pension, you should tell HMRC.

You should tell HMRC if you earned other taxable income (external link) and have not declared it in a Self Assessment (external link) tax return. This could include income from:

renting out property (external link)
capital gains (external link), for example from selling property, valuable items or shares
working for yourself (external link), including if you buy or sell items regularly, for example at car boot sales or on the Internet (you will also need to register as self-employed)

If this income takes you over your Personal Allowance (external link), you will pay tax on it.

Declare the Income on a Tax Return

If you are already registered for Self Assessment but have not declared all your income, you can make a change to your return (external link).

If you do not usually send a tax return, you can register for Self Assessment to declare any income you have not paid tax on from the last 4 years. You’ll need to fill in a separate tax return for each year.

You will get a letter telling you what to do next (external link) after you have registered.

Other Taxes

You must register for:

Corporation Tax (external link) if you run a limited company
VAT (external link) if your taxable annual business turnover is more than £81,000
PAYE for employers (external link) if you employ people

Overseas Income

If you are a resident (external link)in the UK, you may need to report foreign income (external link) in a Self Assessment tax return (external link).

If you do not 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 (external link)’ if:

you have not told them about your foreign income
you are not paying the right amount of tax
you have previously made an incorrect claim
you are behind with your tax

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