VAT registration: do you need to, and when

Most people know VAT registration has a turnover threshold. Fewer realise it's measured on a rolling 12-month basis rather than your tax year or the calendar year, which is where the trap usually is — a strong few months can tip you over without a single "annual" figure ever crossing the line.

The compulsory threshold

Registration becomes compulsory once your VAT-taxable turnover goes over £90,000 in any rolling 12-month period, not a fixed year. You need to register within 30 days of the end of the month in which you went over the threshold, and you become VAT-registered from the first day of the second month after that. Missing this window doesn't remove the liability — HMRC can register you anyway, backdated, which is a far less comfortable position than registering on time.

Registering voluntarily

You can register before you're required to, and there are good reasons some businesses do: it lets you reclaim VAT on costs and equipment, and in some cases it can be backdated to recover VAT on purchases made before registration, within limits. If most of your customers are other VAT-registered businesses, charging VAT usually makes little practical difference to them and can make your business look more established. The right call depends on who your customers are and what you're buying.

What changes once you're registered

You'll need to charge VAT on taxable sales, file returns (quarterly for most businesses) through Making Tax Digital-compatible software, and keep digital records of your VAT transactions. There's also a choice of schemes — standard, flat rate, cash accounting and others — each suited to different kinds of business, which is worth getting advice on rather than defaulting to the first option you see.

What if I go over the threshold temporarily?

If a one-off spike pushes you over £90,000 but you genuinely expect to be back below £88,000 within the next 12 months, you can apply to HMRC for a registration exception rather than registering. This needs evidence to support the expectation, not just a hope — it's worth talking it through before assuming you qualify.

What happens if I register late?

HMRC can charge a penalty based on how late the registration is and how much VAT was due in the meantime. If you think you may already be over the threshold, the right move is to establish the position and register promptly rather than wait — early, voluntary correction is treated far more favourably than being caught out later.