VAT threshold calculator for tradespeople

The rule: any 12 months in a row

You must register for VAT when your taxable turnover for the last 12 months goes over £90,000. It isn't the tax year or your accounting year: at the end of every month, add up the 12 months just gone. A good summer can take you over in August even if the last tax year was well under.

Turnover means your takings, not your profit. For most trades that's everything you charge customers, including the materials you pass on.

You must also register if you expect your turnover in the next 30 days alone to go over £90,000, for example from one big contract.

When you go over

Register within 30 days of the end of the month you went over. Your registration then takes effect from the first day of the second month after it, and from that date you charge VAT and owe it to HMRC.

• GOV.UK's example: the 12-month total first goes over in July. Register by 30 August. Registered from 1 September.
• Register late and you still owe the VAT on sales since the date you should have been registered, and there may be a penalty.
• If you've gone over only for a one-off reason, you can ask HMRC for an exception from registering.

A made-up example

A roofer's takings for the 12 months to the end of September add up to £86,400. The oldest of those months, October last year, was £6,000.

• Headroom now: £90,000 − £86,400 = £3,600
• At the end of October, last October's £6,000 drops out: £86,400 − £6,000 = £80,400 left from the other 11 months
• The most this October can bring in and stay under: £90,000 − £80,400 = £9,600

Check every month, near the threshold. Your day rate may need to change if you register, because most homeowners can't claim the VAT back.

Where this comes from

GOV.UK, Register for VAT: when to register, read on 29 October 2026. Taxable turnover leaves out VAT-exempt and out-of-scope sales; zero-rated and reduced-rated work still counts. Work under the VAT domestic reverse charge for construction counts too.

See your takings month by month

In Knockround, every invoice is on your phone with what's paid and what's owed, and the Money screen shows the month in and out, so the figures for this check are already there. Knockround doesn't do VAT invoices yet, so if you register, check it still fits before you rely on it.

Try it on the plumbing demo, with made-up customers. It's free for 7 days with no card needed, then £19.99 a month.

Written by the Knockround team. This is a guide, not tax advice: HMRC or an accountant can tell you what applies to you.