VAT has no taper. At £89,000 of rolling 12-month turnover your VAT bill is nil; cross £90,000 and, if you sell to consumers, you must either put prices up 20% overnight or hand HMRC roughly one pound in every eight you turn over. In the worked example below, a decorator who grows sales by £6,000 ends up about £5,833 worse off in cash. That is why the threshold is a cliff edge, not a ramp - and why so many firms park themselves just beneath it.
The test is a rolling 12 months, not your accounting year
You must register once taxable turnover for the last 12 months passes £90,000 - any 12 months, checked continuously, not the tax year, the calendar year or your accounting year (GOV.UK, checked June 2026). A busy autumn plus a busy spring can tip you over in February even though no year-end figure ever shows it. HMRC’s own example sets out the timing: rolling turnover passes £90,000 on 15 July; you must register by 30 August; you charge VAT from 1 September.
There’s a second trigger people miss. If you expect more than £90,000 of taxable sales in the next 30 days alone - one large contract can do it - you must register by the end of those 30 days, effective from the day you realised, not the day the money arrives.
Three details with teeth. Taxable turnover includes zero-rated and reduced-rated sales, not just work charged at 20%; only exempt and out-of-scope income stays out of the count. Register late and you owe VAT on everything sold since the date you should have registered (money you never collected from customers), plus a possible penalty. And if the breach was a one-off spike, you can apply for a registration exception.
Crossing costs about 12.5% of turnover - or a 20% price rise
The pounds in this example are illustrative; every rate and threshold is GOV.UK’s. Take a sole-trader decorator working for homeowners, with turnover crossing the line to £95,000 and materials costing £20,000 a year plus £4,000 VAT. Homeowners can’t reclaim VAT, so registration leaves two options.
Pass it on. Every £1,000 quote becomes £1,200 - a 20% rise against under-threshold competitors quoting VAT-free for identical work. If you build prices up from the job, this is one more layer to get right (Price the job, not the day rate).
Hold your prices. Then £95,000 is VAT-inclusive, and the output VAT is one-sixth of it: £15,833. Reclaim the £4,000 input VAT on materials and £11,833 goes to HMRC, about 12.5% of turnover, straight off the bottom line.
So: at £89,000 the VAT bill is £0. Grow by £6,000 with prices held and the £11,833 bill leaves you roughly £5,833 worse off in cash than before you grew. (One simplification: VAT runs from your effective registration date, not back across the whole year, so the first year’s bill depends on when you cross.) Splitting the difference - some price rise, some margin - shares the cliff around; it doesn’t shrink it.
The flat rate scheme suits low-materials firms and traps the rest
The Flat Rate Scheme swaps the in-and-out calculation for a single sector percentage of your VAT-inclusive turnover (GOV.UK). You can join if you expect taxable turnover of £150,000 or less, and there’s a 1% discount in your first year of registration. In exchange, you reclaim nothing on purchases except certain capital assets over £2,000 - and that clause decides everything.
Run the decorator at the 14.5% labour-only construction rate: £95,000 × 14.5% = £13,775, or £12,825 in year one with the discount. Both lose to standard accounting’s £11,833, by £1,942 and £992 respectively, because giving up the £4,000 materials reclaim costs more than the lower headline rate saves. Strip the materials out, though, and it flips: a similar business with just £800 of input VAT would pay £15,033 under standard accounting but £13,775 on the flat rate - a saving of about £1,258, or £2,208 in year one.
Two cautions before joining. First, don’t read your rate off the label: construction counts as “labour-only” at 14.5% only when materials come to less than 10% of turnover for those services; otherwise it’s general building or construction at 9.5%, a different sum entirely. Run your own materials number. Second, the limited cost business rule: if your goods cost under 2% of turnover (or under £1,000 a year), you pay 16.5% whatever your sector. On £95,000 that’s £15,675 - barely below the full £15,833 output VAT, with no input recovery at all. Since 16.5% of a VAT-inclusive price equals 19.8% of the net price, a limited cost trader keeps just 0.2 of the 20 percentage points charged. If you sell labour or expertise and buy little, assume this applies until you’ve checked. You must also leave the scheme once turnover including VAT passes £230,000 at your joining anniversary.
Cash accounting changes when you pay, not how much
The Cash Accounting Scheme fixes timing, not the bill. Standard VAT accounting makes VAT due off the invoice date whether or not you’ve been paid; on cash accounting you pay VAT when customers pay you and reclaim it once you’ve paid your suppliers (GOV.UK). For a newly registered firm with slow payers, that stops you financing HMRC out of money you haven’t received. There’s nothing to apply for - join at the start of a VAT period if your expected taxable turnover is £1.35 million or under. It can’t be combined with the flat rate scheme, which has its own cash-based turnover method.
Hovering under the line is a strategy - make it deliberate
HMRC expected raising the threshold from £85,000 to £90,000 in April 2024 to keep 28,000 micro businesses out of VAT registration in its first year, which gives a sense of how many firms sit pressed against this line. If you’re one of them:
Total the last 12 months’ sales every month. Fold it into the same month-end half-hour as your tax set-aside. The rolling test only ambushes people who aren’t watching it.
Decide your crossing plan before you cross - pass it on, absorb it, or split it - and re-quote accordingly. If most of your customers are VAT-registered businesses rather than consumers, they reclaim what you charge, the cliff largely disappears, and registering voluntarily before you’re forced can be worth considering.
Know the way back down. Below £88,000 of taxable turnover you can ask HMRC to cancel your registration; the £2,000 gap exists, in HMRC’s words, to stop firms “having constantly to register and deregister”. But capping yourself at £89,999 puts a permanent ceiling on the business to dodge a one-off step. If the work is there, the sharper question isn’t how to stay under the cliff - it’s how quickly you can grow past the thin air just above it.
