Free VAT threshold checker

Know how close you are to the VAT cliff — before HMRC tells you.

Cross the £90,000 rolling 12-month threshold without noticing, and HMRC can charge you for every month you should have been VAT-registered. Enter your best, average and worst month below and see where you actually stand.

TL;DR

The VAT threshold is a rolling 12 months, not a tax year — it moves every month. One strong month can tip a spiky business over the line without a single "annual" number ever looking dangerous.

Why the threshold catches people out

Most sole traders think of VAT registration as something that happens at the end of a tax year, once someone adds up the annual total. It doesn't work that way. HMRC tests your turnover against the threshold on a rolling 12-month basis — every month, it looks back at the trailing year, not the calendar or tax year.

That means a business with genuinely seasonal or lumpy income — a big fleet job, a run of MOT-season work, a couple of standout months — can cross the threshold mid-year without a single monthly bank statement ever looking alarming on its own. By the time an accountant catches it at year-end, the 30-day registration window may already have passed.

This checker gives you a directional read using three numbers you already know — your best, average and worst month. It brackets a likely range rather than pretending to HMRC-grade precision, because three numbers genuinely can't reconstruct a true rolling 12-month figure. For that, you need your actual monthly turnover tracked continuously — which is exactly what the ForgeDash app does automatically, watching your real rolling 12 months and warning you well before you get close.

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VAT threshold FAQs

What is the UK VAT registration threshold?

It is currently £90,000 of taxable turnover in any rolling 12-month period — not a tax year, not a calendar year, but a rolling 12 months that moves every month. You must register within 30 days of crossing it.

How is this checker different from a real rolling-12-month test?

This tool works from three numbers — your best, average and worst month — because that's a realistic amount of information to type into a landing page. HMRC's actual test looks at your real turnover for the trailing 12 months, recalculated every month. This gives you a directional estimate, not a filed figure.

What happens if I go over and don’t register?

HMRC can charge a penalty based on how late you register and how much VAT should have been charged in the meantime. Registering on time — within 30 days of crossing the threshold — avoids that entirely.

What if my income is seasonal or unpredictable?

That is exactly why a single "current month" snapshot is risky — one strong month can tip a rolling 12-month total over the line even if most months are quieter. The best/average/worst inputs here are a rough way to sanity-check a spiky business; ongoing monitoring against your real numbers is the only way to know for certain.

Do I need to register before I hit the threshold?

No — registration is only mandatory once you cross it (or expect to within the next 30 days alone). You can register voluntarily earlier if it suits your business, for instance if most of your customers are VAT-registered themselves.

Is this checker free?

Yes, completely free with no sign-up. ForgeDash — the app this calculator previews — watches your real rolling 12-month turnover automatically and warns you before you get close, on the Free plan.