When do I have to register for VAT?

When your VAT-taxable turnover exceeds £90,000 in any rolling twelve-month period, or when you expect to exceed it in the next thirty days alone — the second test can be triggered by a single large order. The rolling nature is what catches people: it is not your accounting year or the calendar year, so it has to be checked monthly. You must register within thirty days of the end of the month in which you crossed the historic threshold, and registration takes effect from the first day of the following month.

What happens if I register late?

HMRC can charge you the VAT you should have collected from the date you should have been registered — money you never took from customers and usually cannot go back and ask for. A failure-to-notify penalty applies on top, calculated as a percentage of that VAT, and reduced substantially where the disclosure is unprompted rather than discovered. On a £120,000 turnover business, several months of unaccounted output VAT is a five-figure bill against margin that has already been spent. Watching the rolling twelve-month figure monthly avoids all of it.

Should I register voluntarily?

It depends on your customers. If they are mainly VAT-registered businesses, they reclaim what you charge, so registration costs them nothing and lets you recover VAT on your own purchases, equipment and overheads — often several thousand pounds a year. If you sell to consumers or small unregistered businesses, you either become 20% more expensive or absorb it and lose a fifth of your margin. There is also the ongoing cost: quarterly returns, digital record-keeping and Making Tax Digital obligations from the day you register.

What is the Flat Rate Scheme?

A simplification for businesses with turnover up to £150,000 excluding VAT, where you pay HMRC a fixed percentage of gross turnover rather than tracking VAT on every purchase, and generally cannot reclaim input VAT except on capital assets over £2,000. It suits low-cost service businesses with few purchases. The limited cost trader rule puts businesses spending under 2% of turnover on goods onto a 16.5% rate, which removes almost all the benefit and catches many consultants. Model it both ways on your actual figures before joining.

Can I avoid crossing the threshold?

You can manage it legitimately — by timing large jobs across periods, or by genuinely limiting trading — but be careful. Artificially splitting one business into two to stay under the threshold is disaggregation, and HMRC can direct that the businesses be treated as one and backdate registration accordingly. The test looks at financial, economic and organisational links, not at whether there are two sets of paperwork. The bigger question is whether you want to run a business capped at £90,000 to avoid a tax your competitors are already charging.

What changes day to day once I am registered?

You charge VAT on your sales, issue compliant VAT invoices, reclaim VAT on business purchases and file a return each quarter, paying the difference — usually one month and seven days after the period ends. Records must be digital and returns filed through compatible software under Making Tax Digital. Practically, the biggest adjustment is cash: the VAT you collect is not your money, and businesses that treat it as working capital get into difficulty at the quarter end. Move it to a separate account as it arrives.

When should you register for VAT?

VAT registration is one of those milestones that feels daunting but often isn't as bad as feared — and sometimes it's worth doing before you're forced to. Here's when you have to register, what it costs you if your customers are the public, when voluntary registration pays, and how to decide on the Flat Rate Scheme using your own numbers rather than a rule of thumb.

When you must register

You're required to register for VAT once your VAT-taxable turnover exceeds £90,000 in any rolling 12-month period — not just your accounting year, but any 12 months. That threshold has applied since 1 April 2024. There is a second, separate test: you must also register if you expect to exceed £90,000 in the next 30 days alone, which a single large contract can trigger on its own.

The deadlines are specific, and worth writing down. If you cross the rolling threshold, you have 30 days from the end of the month in which you crossed it to notify HMRC, and your registration takes effect from the first day of the month after that. So if your rolling turnover tipped over £90,000 during March, you must notify by 30 April and you are VAT-registered from 1 May. The forward-look test is tighter still: you register immediately, and you are VAT-registered from the date you formed the expectation — not from the date the money arrives.

Once registered, you charge VAT on what you sell, reclaim VAT on what you buy, and file returns digitally under Making Tax Digital, usually quarterly. Payment is normally due one month and seven days after the quarter ends.

The trap of not watching your rolling turnover

Because the threshold is based on a rolling 12 months, it is easy to cross without noticing if you only look at year-end figures. The fix is a two-minute monthly habit: add up the last 12 months of taxable sales, including the month that has just closed, and drop the month that has just fallen out of the window.

Here is what that looks like for a business growing steadily. Take a trade business billing £6,500 a month a year ago and £8,500 a month now. Its accounting year-end figure might read £88,000 and look comfortable. But the rolling 12 months to the end of July — dropping last August's £6,500 and adding this July's £8,500 — reads £90,000 exactly, and the rolling 12 months to the end of August reads over £91,000. The business crossed in August, must notify HMRC by 30 September, and is registered from 1 October. Looking only at the year end, the owner would not have found out until the accounts were prepared, by which point five months of sales had gone out without VAT on them.

Register late and HMRC can assess the VAT you should have collected from the date you should have been registered — money you never charged your customers and usually cannot go back and ask for. A failure-to-notify penalty sits on top of that, and it is substantially lower where you tell HMRC before they find it.

What crossing costs when you sell to the public

If your customers are VAT-registered businesses, crossing the threshold is close to neutral: they reclaim what you charge. If your customers are consumers, it is a genuine hit, and it is worth sizing before it happens.

Say you turn over £92,000 a year selling to the public and you cannot raise your prices — the market sets them. Your £92,000 of gross sales is now £76,667 of net income and £15,333 of VAT you hand to HMRC. Against that, you reclaim VAT on your own standard-rated costs: if those run at £12,000 including VAT, you recover £2,000. The net cost of registration is around £13,333, or roughly 14% of turnover, and it lands on the margin, not the top line. Businesses in this position are the ones for whom the £88,000 deregistration threshold matters — if taxable turnover falls below £88,000, you can ask HMRC to cancel your registration.

Registering voluntarily below the threshold

You can register below £90,000, and for a decent number of businesses it is the better call. The test is who your customers are.

Take a consultancy turning over £60,000, selling entirely to VAT-registered companies. Registering costs those clients nothing — they reclaim the VAT you add. On the other side, you recover the VAT on your own purchases. If you spend £14,000 a year including VAT on software, equipment, professional fees and travel, that is around £2,333 recovered annually that you were previously absorbing. There is also a one-off gain at registration: you can generally reclaim VAT on goods you still hold that were bought in the four years before registering, and on services in the six months before.

The costs are real too — quarterly returns, digital record-keeping, and the discipline of not spending money that belongs to HMRC. The single most useful habit for a newly registered business is to move the VAT element of each payment received into a separate account the day it arrives.

The Flat Rate Scheme, and the rule that catches consultants

The Flat Rate Scheme simplifies VAT for smaller businesses. You can join if your taxable turnover excluding VAT for the next year will be £150,000 or less. Instead of tracking VAT on every purchase, you pay HMRC a fixed percentage of your gross (VAT-inclusive) turnover, set by your trade sector, and you generally cannot reclaim input VAT — except on a single purchase of capital goods costing £2,000 or more including VAT. There is a 1% reduction in your flat rate percentage for the first 12 months after registration. You must leave the scheme when your VAT-inclusive income for the year then ending exceeds £230,000, or when you expect it to exceed £230,000 in the next 30 days alone.

The rule that trips people up is limited cost business. If your spending on relevant goods, including VAT, is either less than 2% of your flat rate turnover, or more than 2% but less than £1,000 a year, your rate is 16.5% whatever your sector. Services do not count as goods, and nor do capital items, food and drink for staff, or vehicle costs in most cases. Consultants, coaches, designers and copywriters — anyone whose costs are almost entirely other people's time and software — land here routinely.

Worked example: a limited cost consultant, both ways

A marketing consultant turns over £96,000 excluding VAT, so £115,200 including VAT at 20%. She spends £6,000 excluding VAT a year on standard-rated costs, almost all of it software subscriptions and accountancy fees. These figures are illustrative, but the arithmetic is the arithmetic.

Standard VAT accounting: output VAT of £19,200, less input VAT of £1,200 on her costs, so £18,000 payable to HMRC across the year.
Flat Rate Scheme as a limited cost business: 16.5% of £115,200 = £19,008, with nothing reclaimable.

The Flat Rate Scheme costs her £1,008 a year more, and she still has to work out whether she is a limited cost business each quarter. In her first year of registration the 1% discount takes the rate to 15.5%, or £17,856 — £144 better than standard accounting, and only for twelve months. The decision rule is simple: if your VAT-inclusive spending on goods is under 2% of turnover, price the Flat Rate Scheme at 16.5% before you assume it saves you anything.

Four questions to answer this week

What is my rolling 12-month taxable turnover today? Not the year-end figure. Put the calculation in your bookkeeping software or a spreadsheet and check it on the first of every month.
Is there a single job in my pipeline that would push me over £90,000 within 30 days? If so, the forward-look test applies and the clock starts when you form that expectation.
Who are my customers? Add up what share of your sales go to VAT-registered businesses. Above roughly 80%, voluntary registration is usually worth modelling. Below 20%, crossing the threshold will cost you real margin and you should know the number in advance.
What did I spend on goods last quarter, including VAT? Under 2% of turnover, or under £1,000 a year, and the Flat Rate Scheme means 16.5% for you.

One thing to be careful about: deliberately splitting one business into two to keep both under £90,000 is disaggregation. HMRC can direct that the businesses be treated as a single entity and backdate registration, and the test looks at financial, economic and organisational links rather than at whether there are two sets of paperwork.

Get the timing and scheme right

VAT is one of those areas where getting the timing and the scheme choice right saves real money, and getting it wrong costs it. We help businesses register at the right moment, choose the scheme that actually suits them, and set up the digital record-keeping so returns are painless. Try our VAT calculator for the day-to-day maths, read our fuller guide to VAT registration or the notes on VAT for online sellers if you sell through marketplaces, and see what late returns actually cost before you let one slip. When registration is on the horizon, talk to us.

When should you register for VAT? (and the Flat Rate Scheme)