Track your rolling 12-month turnover against the £90,000 VAT registration threshold. See headroom remaining.
Source: GOV.UK — Register for VAT
By Konstantin Iakovlev · Founder, Calks.uk
Last updated: · Verified against HMRC and GOV.UK 2026/27 rates
Rates verified: 28 September 2026
Rolling 12-Month Turnover
£72,000.00
£18,000.00 headroom before VAT registration
% of Threshold
80%
Avg Monthly
£6,000.00
Goes Over Threshold
Never at this run-rate
Projection assumes each future month brings in £6,000.00. The rolling total is always the latest 12 months, so a steady business only goes over if it averages more than £7,500 a month.
Disclaimer
This calculator is for guidance only. It is not financial or tax advice: check anything you rely on against the official source or a qualified adviser. Rates and figures come from HMRC and GOV.UK and are reviewed for the 2026/27 tax year. Everything is calculated in your browser; nothing you enter is sent to our servers.
How It Works
VAT registration in the UK does not follow your accounting year. What matters is the rolling total of taxable turnover for the last 12 calendar months, tested afresh every month, measured against the £90,000 registration threshold. The monitor keeps that running total in front of you, shows how much headroom is left and projects when, at your current monthly figure, you would go over it. Everything you type stays in the browser and nothing is sent to a server, so you can try several versions of a busy trading year without any of it being stored.
Working out the rolling figure means adding up taxable turnover for the last 12 months, so a check made at the end of August 2026 covers everything from 1 September 2025 through 31 August 2026. Once the total goes over £90,000 you must register within 30 days of the end of the month in which you went over, and your registration takes effect from the first day of the second month after it. Go over on 15 March 2026, with the 12 months to 31 March 2026 as the test period, and registration is due by 30 April 2026, with VAT chargeable on sales from 1 May 2026.
The £90,000 figure has applied since April 2024, when it rose from £85,000 in the first increase since 2017. Deregistration works on a separate, lower number. Fall below £88,000 and stay there for 12 months and you can leave the system again. Registration is also open voluntarily at any level of turnover, which is a real option rather than a formality for some businesses.
A second test looks forward rather than back. Where you know that in the next 30 days alone your taxable sales will exceed £90,000, registration is immediate, even if the rolling 12-month total is nowhere near it. Winning a £100k contract in early April triggers this, so you register before the work starts although the trailing year shows only £70k. The forward rule exists to stop a single large job dragging a business into VAT halfway through a month.
Missing registration is expensive, because HMRC backdates the charge to the day you should have registered. You then owe VAT on everything sold since that date whether or not you charged it to customers, and few customers will settle a retrospective invoice, so it comes out of your margin. On top of that sits a failure-to-notify penalty, charged as a percentage of the VAT lost: up to 30% if the failure was not deliberate (which can fall to nil if you tell HMRC unprompted within 12 months), 20% to 70% if deliberate, and 30% to 100% if deliberate and concealed. Register 6 months late with £20k of sales behind you and that is about £3,333 of VAT, since the price you were paid is treated as including VAT, plus interest before any penalty is counted.
Voluntary registration can pay off well before the threshold, and the Flat Rate Scheme changes the sums again. A business selling mainly to other VAT-registered companies loses little by registering, since those customers reclaim whatever you charge, and anyone carrying heavy input VAT on equipment, supplies or services gets that money back. Selling to consumers is the opposite case, because adding 20% either raises your prices or eats your margin. The Flat Rate Scheme, open below £150k of turnover, swaps the usual input and output calculation for a fixed percentage of gross turnover and much less paperwork, although a 16.5% rate introduced in 2017 removed most of the benefit for service businesses.
Example: new business turning over £8,000 a month
- Six months of trading at £8,000 a month: rolling 12-month turnover £48,000
- After 11 months the total is £88,000, which is not over £90,000
- Month 12 takes it to £96,000, so the business goes over the threshold 6 months from now
- Register within 30 days of the end of that month; VAT applies from the first day of the second month after it
- An established business steady at £6,000 a month sits at £72,000 and never goes over; only an average above £7,500 a month does
Source: GOV.UK — Register for VAT
Frequently Asked Questions
- When does my turnover force me to register for VAT?
- Once taxable turnover for the last 12 months goes over £90,000. You then have 30 days from the end of the month in which you went over to register, and registration takes effect from the first day of the second month after you went over: go over on 15 July, register by 30 August, and VAT applies from 1 September. Registering online through gov.uk/register-for-vat usually produces a VAT number within about 10 days. From the effective date you charge VAT on standard-rated supplies and file returns, normally quarterly, under Making Tax Digital.
- Do I have to register before I even reach £90,000?
- Sometimes. If you expect taxable sales in the next 30 days alone to exceed £90,000, registration is required straight away, regardless of what the trailing 12 months show. Winning a £100k contract in early April is the classic case, since you register before the work begins even though the rolling total sits at only £70k. Without that rule a single large job would pull a business into VAT partway through a month.
- What is the penalty for registering for VAT late?
- HMRC charges a failure-to-notify penalty as a percentage of the VAT lost: up to 30% where the failure was not deliberate, 20% to 70% where it was deliberate, and 30% to 100% where it was deliberate and concealed. Telling HMRC yourself, and within 12 months, keeps it at the low end, and a reasonable excuse means no penalty. Worse than the penalty itself is the backdating, because HMRC treats VAT as due from the date registration should have taken effect. Six months late on £20k of sales means about £3,333 of VAT, a sixth of what you were paid, plus interest, and customers rarely agree to pay a charge raised after the event.
- Should I voluntarily register for VAT below £90,000?
- It depends who buys from you. Where most customers are VAT-registered businesses they reclaim the tax, so charging it costs them nothing while you recover input VAT on your own costs. Sellers of zero-rated goods such as children's clothes, books and most food gain the most, reclaiming input VAT while customers pay 0%. The answer is usually no when your buyers are consumers or unregistered businesses, when your supplies are exempt, or when admin capacity is already stretched.