What counts as side income
Freelancing, online selling as a trade, content income, delivery work and other paid activity can create taxable income. Selling personal possessions is not automatically trading, and the facts of the activity matter.
Trading allowance or actual expenses
A trading allowance may cover a limited amount of gross trading income. Where actual allowable expenses are higher, claiming those costs instead may produce a lower taxable profit. The two approaches should not be claimed against the same income.
When Self Assessment may be needed
Side income above relevant allowances may need to be reported to HMRC. Registration and filing requirements depend on gross income, profit, other income and the nature of the activity.