VAT threshold
When do you cross the VAT threshold?
The £90,000 test isn't about the tax year — it's any rolling 12 months, checked at the end of every month. Put in your last 12 months and a typical month, and see whether you're on course to cross, and roughly when. There's a second test this calculator can't do for you: if you expect to take more than £90,000 in the next 30 days on its own, you must register immediately, whatever the last 12 months say.
Your turnover
VAT-taxable turnover over the last 12 rolling months, not the tax year. Leave out anything exempt or outside the scope of VAT.
What a recent month's invoicing adds up to.
Two numbers can only get you so far: this assumes the last 12 months were even, and that every month from here runs at the pace you gave. A rolling year replaces one month at a time, so after 12 months the total is simply 12 months at that pace. Registration threshold £90,000, checked against GOV.UK on 20 August 2026.
The rolling window is the trap
Most people picture the threshold as a tax-year total that resets in April. It doesn't reset. At the end of every month you look back exactly 12 months, and if that total is over £90,000, the clock has already started. A busy autumn on top of a decent spring can carry you over in a month where you barely worked — the window remembers the whole year even when the diary doesn't.
A worked example
Say the last 12 months add up to £76,000 and a typical month lately is £8,000. Each new month adds £8,000 and drops an average old month of about £6,333, so the rolling total climbs roughly £1,667 a month. The £14,000 of headroom runs out in about nine months — not the two or three that £8,000 a month against £14,000 might suggest, and not never, which is what "I'm only at £76,000" feels like.
That climb doesn't go on forever, and the ceiling is worth knowing. The window only has 12 old months to shed. Once they've all gone, the rolling total is just 12 months at your current pace — £96,000 here — and it stops moving. Drop the pace to £7,000 and the year settles at £84,000, which is under the threshold: at that rate you never cross it, however long you keep going. Growth on its own doesn't take you over. Twelve times a typical month is what decides it.
What happens when you cross
You must register within 30 days of the end of the month you went over, and you charge VAT from the first day of the month after that deadline. Cross in July: register by 30 August, VAT from 1 September. Crossing isn't a disaster — it's a pricing decision you want to make ahead of time rather than discover in arrears. If you're close, the flat rate comparison is the next question worth an answer.
grafter.ly keeps every invoice in one place, so the 12-month number stops being a guess. Once you're over, the VAT page shows what you've charged and what you've paid out, by quarter. How the VAT quarter works.
Know where the year is heading.
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