Tell HM Revenue and Customs (HMRC) as soon as possible if you’ve 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, they may consider your case more favourably.
You do not need to tell HMRC about income you’ve 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 and have not declared it in a Self Assessment tax return. This could include income from:
If you’re already registered for Self Assessment but have not declared all your income, you can make a change to your return.
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.