There are two tests, the history test and future test, that determine if a UK business needs to register for VAT. The history test looks at the total value of taxable supplies over the previous 12 months, and if it exceeds £82,000 the business must register. The future test requires registration if the business expects to exceed £82,000 in taxable supplies in the next 30 days. If both tests are passed, the earlier registration date must be used. Businesses must notify HMRC within 30 days if either test is passed to avoid penalties for late registration. Voluntary registration is also allowed if turnover is below the compulsory threshold.