The VAT Registration Threshold: When You Must Register

When do you have to register for VAT? The headline number is £90,000, but the threshold is not one line you cross on one day. HMRC runs two separate tests: a backward-looking check on your last 12 months of taxable turnover, and a forward-looking check on the next 30 days alone. Each has its own deadline and its own effective date, and the forward test can make you register before you have taken a single extra pound. This guide walks both tests as dated examples, then covers the exception for a one-off spike, whether to register voluntarily, and what it costs if you leave it too late.

What the VAT registration threshold is

The VAT registration threshold is the level of taxable turnover above which registering for VAT stops being optional. It rose from £85,000 to £90,000 on 1 April 2024 and has stayed there since, per HMRC's policy paper on the threshold increase.

The figure that matters is taxable turnover, not profit and not total sales. HMRC counts "the total value of everything you sell that is not VAT exempt or 'out of scope'", which includes your standard-rated, reduced-rated and zero-rated supplies, goods you hire or loan to customers, business goods used for personal reasons, and services you receive that fall under the reverse charge. Exempt supplies such as most insurance, finance and certain education do not count. The full list is on the gov.uk page for working out your VAT taxable turnover.

A sole trader billing £7,000 a month for standard-rated services is running at £84,000 a year and sits below the line. Add one recurring client at £700 a month and the annual run rate is £92,400, which is where the tests below start to bite.

The two tests that trigger registration

HMRC's rule has two limbs, and you must register if either one is met. The gov.uk guidance on when to register states you must register if "your total taxable turnover for the last 12 months goes over £90,000" or "you expect your taxable turnover to go over £90,000 in the next 30 days".

The 12-month test is a rolling one. You check the trailing twelve months at the end of every month, not the tax year or your accounting year, so a strong autumn can push you over in a month you were not watching.

The backward look, worked through

Say your rolling 12-month turnover first passes £90,000 at the end of May 2026, reaching £92,000. You have until 30 June 2026, thirty days after the end of that month, to tell HMRC. Your registration takes effect from 1 July 2026, the first day of the second month after you crossed the line. From 1 July you charge VAT on your standard-rated sales and can reclaim VAT on your costs.

The forward look, worked through

The forward test is the one that surprises people, because it can trigger before your annual turnover is anywhere near £90,000. Imagine that on 10 June 2026 you sign a single contract worth £100,000 to be invoiced within the next month. You now expect to go over £90,000 in the next 30 days on that one deal, so you must register by 9 July 2026, and your registration is effective from 10 June 2026, the day you realised. Every invoice you raise from 10 June carries VAT, including the £100,000 contract that set off the test.

The exception for a temporary spike

Going over the threshold once does not commit you to staying registered. If a one-off event pushes your rolling turnover over £90,000 but you can show it will drop straight back, you can apply for a registration "exception". HMRC grants it where your taxable turnover went over the registration threshold in the last 12 months but you can demonstrate it will not go over the £88,000 deregistration threshold in the next 12 months.

You have to write to HMRC and make the case; the exception is not automatic. HMRC replies within 40 working days, telling you whether it has been approved. Miss that window of opportunity and you register as normal. A caterer who takes a single £30,000 wedding contract in an otherwise £75,000 year is the textbook case: the spike is real, but the twelve months ahead clearly stay under £88,000.

Registering voluntarily below the threshold

You can also register when you are nowhere near £90,000. HMRC's guidance on registering is explicit: "You can choose to register for VAT if your turnover is less than £90,000." Voluntary registration lets you reclaim the VAT on your business costs, and it can make a young business look more established to VAT-registered customers who reclaim the VAT you charge them anyway.

It is a trade-off, not a free win. Once registered you charge 20% on standard-rated sales, which raises your price to any customer who cannot reclaim it, and you take on the quarterly return and the digital record-keeping that comes with it. Register voluntarily when most of your customers are themselves VAT-registered businesses and you carry real input VAT on stock or equipment; hold off when you sell mainly to consumers who see a 20% price rise and have nothing to reclaim.

What registering late costs

The threshold is a legal obligation, so missing it is not a paperwork slip that gets waved through. Two costs stack up.

First, the VAT itself. HMRC's rule is blunt: "If you register late, you must pay VAT on any sales you've made since the date you should have registered." That output VAT is due whether or not you charged it, so on £30,000 of standard-rated sales made after your effective date you owe £30,000 × 20% = £6,000, and you usually cannot go back to customers months later to collect it. It comes out of your margin.

Second, a penalty. Late registration is a "failure to notify", and HMRC charges a penalty worked out as a percentage of the "potential lost revenue", the tax that went unpaid because you did not register on time. The percentage depends on behaviour and on how you come forward, set out in the failure to notify penalty factsheet:

Coming to HMRC before it comes to you is what keeps a non-deliberate slip at the bottom of that range, and HMRC will not charge a penalty at all where you had a reasonable excuse for a non-deliberate failure. The lesson is to watch the rolling twelve months yourself rather than wait for a letter.

What changes once you cross the threshold

Registration is the start of an ongoing routine, not a single form. From your effective date you charge the right rate of VAT on every sale, 20% standard on most goods and services, and you reclaim the VAT on your own purchases where you hold a valid VAT invoice. You file a VAT Return, normally every quarter, showing the VAT you charged less the VAT you are reclaiming.

Those records must be digital. Every VAT-registered business now falls under Making Tax Digital for VAT, which means keeping your VAT records digitally and filing returns through compatible software rather than by typing figures into the HMRC portal. Our guide to Making Tax Digital covers what qualifies, and the deeper mechanics of a compliant VAT trail sit in our VAT record-keeping requirements guide.

Turnover can fall as well as rise. If your taxable turnover drops below the £88,000 deregistration threshold you can ask HMRC to cancel your registration, which is why the deregistration line sits £2,000 below the £90,000 registration line: it stops a business that hovers around the threshold from registering and deregistering every few months.

How SparkReceipt keeps your VAT records ready

The moment you register, every receipt becomes a VAT reclaim you do not want to lose, and every sale becomes VAT you have to account for. Miss the input VAT on a year of purchases and you hand HMRC more than you owe.

SparkReceipt scans receipts and invoices with AI and reads the VAT, the net, the date and the supplier off each one, applying the UK's VAT treatment automatically so the tax is captured rather than guessed later. Its expense reports pull those figures into tax summaries you can hand to a bookkeeper or feed into your return, and it keeps a digital record ready for Making Tax Digital. When your books live in QuickBooks or Xero, receipts and their VAT sync straight through the QuickBooks Online integration with the tax codes intact. You can start on the free plan and see the pricing plans as your VAT record-keeping grows.

Frequently asked questions

Is the VAT registration threshold based on turnover or profit? Turnover. Specifically your taxable turnover, the total value of the goods and services you sell that are not VAT exempt or out of scope. Your costs and profit do not enter the calculation; a business can be loss-making and still be required to register.

Does the £90,000 threshold run on the tax year? No. The backward-looking test is a rolling 12-month figure that you check at the end of every month, so it can be triggered part-way through your accounting year. The forward-looking test looks at a single 30-day window regardless of the calendar.

What is the difference between the £90,000 and £88,000 figures? £90,000 is the registration threshold, the point at which you must register. £88,000 is the deregistration threshold, the point below which you can ask to cancel your registration. The gap keeps businesses near the line from switching in and out repeatedly.

Can I avoid registering if I only went over once? Possibly. You can apply for a registration exception if you can show your taxable turnover will stay below £88,000 over the next 12 months. HMRC decides case by case and replies within 40 working days; you must apply rather than assume.

What happens if I register a few months late? You must pay the VAT due on your sales from the date you should have registered, often out of your own margin because you did not charge it at the time, plus a failure-to-notify penalty. Telling HMRC before it contacts you keeps a non-deliberate penalty at the low end of the range.

Do I have to use software once I register? Yes. All VAT-registered businesses fall under Making Tax Digital for VAT and must keep digital VAT records and file returns through compatible software rather than keying figures into the HMRC website.

Key takeaways

• The VAT registration threshold is £90,000 of taxable turnover, raised from £85,000 on 1 April 2024, and taxable turnover means sales, not profit.
• Two tests trigger registration: the backward-looking rolling 12-month test and the forward-looking single-30-day test. Either one is enough.
• The backward test gives you 30 days from the month-end to register, effective the first day of the second month; the forward test makes you effective from the day you realised.
• A one-off spike can qualify for a registration exception if you show turnover stays below the £88,000 deregistration line over the next 12 months.
• Register late and you owe the VAT from your effective date, usually from your own margin, plus a failure-to-notify penalty of up to 30% for a non-deliberate slip.
• Once registered you charge VAT, file quarterly, and keep digital records under Making Tax Digital, so capturing the VAT on every receipt from day one is what keeps the return honest.