The £90,000 VAT threshold: a rolling trap, and what to do as you approach it

The single most common VAT mistake isn't on a return: it's registering late, because the threshold doesn't work the way most people assume.

It's a rolling 12 months, not your trading year

You must register when taxable turnover in any rolling 12-month period exceeds £90,000, checked continuously, not at your year end. A strong six months can tip you over mid-year while your annual accounts still look comfortably under.

There's a second trigger people forget entirely: if you expect to exceed £90,000 in the next 30 days alone (a single big contract, say), registration is immediate.

What late registration costs

Register late and HMRC treats you as registered from the date you should have been. That means:

• VAT owed on everything you sold since that date, which you almost certainly didn't charge your customers
• A failure-to-notify penalty on top, scaled to how late and how deliberate
• The awkward choice between absorbing the VAT (a straight hit to margin) or attempting to re-invoice customers

For a business six months late at £100k turnover, the bill is typically five figures. Monitoring is dramatically cheaper.

Approaching the line? Your options

• Register and choose the right scheme. Standard quarterly accounting, the flat rate scheme (simpler admin, a fixed percentage of gross turnover; sometimes cheaper, often not since the limited-cost-trader rules), cash accounting (pay VAT when customers pay you; kind to cash flow), or annual accounting.
• Register voluntarily early. If your customers are VAT-registered businesses, they reclaim what you charge, and you unlock input VAT on your own costs. For B2B businesses, waiting for the threshold is often the wrong call.
• Deliberately staying under? Legitimate for some lifestyle businesses, but "disaggregation" (splitting one business into two to dodge the threshold) is a well-worn path HMRC knows intimately. Don't.

The practical fix

Put rolling-12-month turnover on a monthly dashboard: one cell in your cloud software. Our bookkeeping clients get this monitored for them, and our VAT service handles registration, scheme choice and every return after it.

This article is general information, not advice for your specific circumstances. For advice you can act on, book a free consultation or call us on 0151 944 4342.