AI agents for business finance: what they can and can't do
What AI agents can do in bookkeeping, close, collections and compliance today, where a person must stay in charge, and how to judge a product.
The short answer
UK businesses must register for VAT when taxable turnover over the previous 12 months goes above £90,000, or when they expect it to go over in the next 30 days alone. Because the test rolls forward every month, an AI agent that recalculates it daily from your sales records can warn you early, but the decision to register, and what to charge customers, stays with you and your adviser.
How the VAT registration test works
HMRC's threshold for compulsory VAT registration is £90,000 of taxable turnover. Two tests apply. The backward-looking test asks whether your taxable turnover for the last 12 months has gone over £90,000; it is a rolling total, not the tax year or your accounting year. The forward-looking test asks whether you expect turnover in the next 30 days alone to go over £90,000, for example because one large contract will be paid at once.
If the backward test is met, you must register within 30 days of the end of the month in which you went over. Your registration date is the first day of the second month after you went over. Miss it and HMRC can ask for the VAT you should have charged, whether or not you collected it from customers, plus possible penalties.
| Test | Trigger | When to register |
|---|---|---|
| Rolling 12 months | Taxable turnover in the last 12 months over £90,000 | Within 30 days of the end of the month you went over |
| Next 30 days | Expected turnover in the next 30 days alone over £90,000 | By the end of that 30-day period |
| Deregistration | Expected turnover in the next 12 months under £88,000 | You may apply to cancel |
Why growing businesses miss it
- They watch the tax year, not the rolling 12 months. A strong spring can push the rolling total over in a month nobody was checking.
- They count the wrong figure. Taxable turnover includes zero-rated sales but excludes exempt and out-of-scope sales. Getting this wrong in either direction causes trouble.
- Revenue arrives in several places: a card terminal, a marketplace payout, a bank transfer, a foreign currency account.
- Nobody owns the check. The bookkeeper looks backwards at quarter end; the owner looks forward at the pipeline.
How an agent watches the threshold
This is a natural job for an agent because it is a calculation that must be redone often from records that change daily. A well set-up agent will:
- Pull every sale from every account and marketplace into one ledger, converting foreign currency sales to sterling consistently.
- Classify each sale as taxable, exempt or outside scope according to rules you and your adviser agreed.
- Recalculate the rolling 12-month total each day and show the headroom left before £90,000.
- Look ahead at signed contracts and large expected payments for the 30-day test.
- Warn you at levels you choose, such as £75,000 and £85,000, and put registration on the compliance calendar if the line is crossed.
The agent should not register you, change your prices or start adding VAT to invoices on its own. Those are decisions with commercial consequences: whether to absorb VAT or pass it on, whether a voluntary registration makes sense, which VAT scheme suits you.
The same daily figure is useful in the other direction. A business that registered voluntarily, or whose sales have fallen, can see when expected turnover for the next 12 months drops below the £88,000 deregistration threshold, and ask an adviser whether cancelling makes sense.
What to give the agent so the number is right
- Every place money comes in: bank accounts, card terminals, marketplaces, payment links and foreign currency balances.
- A list of sales types and how each is treated for VAT, agreed once with your accountant.
- Signed contracts and large expected payments, so the 30-day test is not missed.
- Whether you are part of a group or have other businesses, because HMRC can look at artificial separation of a business to keep under the threshold. That is a question for an adviser, not an agent.
A worked example: a café growing past the line
This is an illustrative example. A café in Brighton had £78,000 of taxable sales in the 12 months to March. Summer trade is strong. The agent's daily figure moves to £84,500 by the end of May and £91,200 by the end of June, so the backward test is met in June. The agent raises it to the owner on 1 July with the working, a note that the registration window closes on 30 July, and a reminder that the registration date will be 1 August.
The owner and accountant then decide how to handle prices. Many hospitality businesses face a choice between raising menu prices and absorbing some VAT. The agent can model both using the café's own sales mix, showing the margin on each menu line at the new price; the owner chooses. Once registered, the agent switches the café's records to VAT coding from the registration date, not before, so the first return starts cleanly.
Where Pryme fits
Sales into a Pryme Business account land in the currency they were sent in, on one ledger the Finance agent keeps as you trade. The Compliance agent can hold a VAT threshold watch as an obligation with its own warning levels and owner, and the Chief of Staff brings the decision to you. If VAT will fall in the same week as payroll, read Cash flow forecasting for UK small firms, and for the wider picture see AI agents for business finance.
Questions people ask
What is the UK VAT registration threshold?
£90,000 of taxable turnover in a rolling 12-month period, or expected turnover over £90,000 in the next 30 days alone. Check HMRC for the current figure.
Do zero-rated sales count towards the threshold?
Yes. Zero-rated sales are taxable supplies and count. Exempt and out-of-scope sales do not.
What happens if I register late?
HMRC can charge the VAT you should have accounted for from the date you should have been registered, plus possible penalties, even if you did not charge customers.
Can I register voluntarily below the threshold?
Yes. Some businesses do so to reclaim input VAT or because their customers are VAT-registered. Whether it suits you is a question for an adviser.
Sources
- Register for VAT: when to register · accessed Oct 2026
- VAT registration: how to register · accessed Oct 2026
- Cancel your VAT registration · accessed Oct 2026
This article is general information, not financial, legal or tax advice. Products described are provided under the terms on this site and are subject to regulation and eligibility.