The two main tests
UK-established businesses generally need to register when taxable turnover exceeds £90,000 over a rolling 12 months, or is expected to exceed £90,000 in the next 30 days alone. Zero-rated sales count toward taxable turnover. Different rules can apply to non-established businesses.
Timing matters
For the backward-looking test, apply within 30 days after the end of the month of exceeding the threshold; registration generally starts on the first day of the second following month. The forward-looking test has different timing: the effective date is when the expectation arose. Check HMRC’s exact rules for your circumstances.
Prepare a review pack
Keep a month-by-month sales schedule, a breakdown by VAT treatment, and notes on unusual contracts. Record the date you first identified the issue. That evidence makes it easier to discuss the correct registration date and what must change in pricing and invoicing.
Next steps for the business
Review quotes, customer communications, accounting software and supplier invoices together. Registration affects processes as well as a calculation. Voluntary registration or an exception may be relevant in some cases, but the threshold calculator cannot assess those options or complete an application.
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FAQs
When must I register for VAT?
You must register when your taxable turnover for the last 12 months exceeds £90,000 — this is a rolling test, checked at the end of every month — or if you expect taxable turnover to exceed £90,000 in the next 30 days alone.
How do I register for VAT?
Most businesses register online through their Government Gateway account. You will need details of your business, its bank account and its expected turnover. HMRC then sends your VAT registration certificate with your VAT number, usually within about 30 working days.
Can I register for VAT voluntarily?
Yes. If your turnover is below £90,000 you can register voluntarily, as long as you make (or intend to make) taxable supplies. Voluntary registration lets you reclaim VAT on your purchases, but you must charge VAT on your sales and file returns.
When can I deregister from VAT?
You can cancel your registration if your taxable turnover falls below £88,000 in the next 12 months, or if you stop making taxable supplies. You must tell HMRC within 30 days of becoming eligible to cancel.
Can I reclaim VAT on things I bought before registering?
Yes, within limits. You can claim VAT on goods bought up to 4 years before registration if you still have them, and on services bought up to 6 months before, provided they relate to taxable supplies you make after registering. The claim goes on your first VAT return.
Official sources
Sources checked: 2026-09-26. Check the official guidance for later changes.
Educational information and estimates. These tools do not submit VAT returns or determine the treatment of a specific transaction.