If someone has earned more than the £1,000 trading allowance from their side hustle in a tax year, they may need to complete a self-assessment tax return. It said an online tool on gov.uk can help people earning extra money to check if and when they need to report their additional income. Kevin Hubbard, HMRC's director of small business and individuals, said: "For many people, a side hustle is a valuable source of extra income. "You can check if you need to do a self-assessment tax return by using the tool on gov.uk. "It takes minutes to use, tells you exactly what you need to do and means no unexpected tax bills later."