A Self Assessment is the method that we use to do personal tax returns in the UK. When you earn untaxed income, you have to declare it to HMRC yourself. You then submit a Self Assessment, detailing all your income and expenses. You pay tax on your profits.
What income is untaxed?
There are various reasons that you might have earned untaxed income. Here are a few of them:
Rental income
Capital gains from investments
Profit from selling assets (e.g. a house)
Self-employed income
Side gig income (e.g. you work full time but drive for Uber on the side)
Claiming pension tax relief
You earn more than £100,000
How to file a Self Assessment
You’re taxed on income that you earn each tax year. This runs from 6th April – 5th April every year, but you can choose to calculate it based on any 12 month period. If you do decide to do this, we’d recommend getting in touch with an accountant as this method can be more complicated – and you want to avoid getting unnecessary penalties.
You have to pay your tax bill by 31st January, the year following the tax period you’re paying for. For income earned between 6th April 2022 – 5th April 2023, for instance, you have to pay your bill by 31st January 2024.
You can pay your tax bill in various ways:
Online using a tax return service
Using an accountant
You can do it yourself via HMRC online, or by post