VAT threshold checker
Twelve months of turnover in, and where you stand against the £90,000 rolling test.
£18,000
£72,000 rolling 12 months
At this rate the rolling total never reaches the threshold.
It's a rolling window, not a tax year. This is the part that catches people out, and it's why most VAT calculators give the wrong answer. The test is your total taxable turnover for the last 12 months, recalculated at the end of every month. You can be under £90,000 in every calendar year you've ever traded and still have gone over on a rolling window inside one of them.
What counts. Everything you sell that isn't exempt or outside the scope of VAT — including zero-rated sales. Zero-rated is not the same as exempt: it's taxable at 0%, and it counts towards the threshold. Leaving it out is the second most common way to get this wrong.
If you go over. You must tell HMRC within 30 days of the end of the month you crossed in, and you're registered from the first day of the second month after that. Go over in July and you register by 30 August, effective 1 September.
Going back under doesn't deregister you. The deregistration threshold is £88,000, deliberately lower than the registration one so businesses hovering around it aren't registering and deregistering every month. Coming off is a choice you have to make, not something that happens.
Figures for 2026/27, checked against gov.uk on 2026-08-07. This is arithmetic, not advice — if you're near the line, the answer is worth an accountant.