VAT registration sits in the background of a solo consulting business until a good quarter or a big contract pushes you near the threshold. Once you're close, it affects your pricing, your cash flow and how you come across to bigger clients.

Below are the two tests that force registration, their deadlines, and what changes once you're registered. It isn't formal tax advice. Confirm the details with HMRC or a qualified adviser, and use this to ask sharper questions and keep your numbers ready.

The threshold: £90,000 of taxable turnover. HMRC can change it, so check the current figure on GOV.UK's VAT registration guidance before you rely on it.

How the UK VAT threshold works

The registration test runs on a rolling 12 months, not your calendar year or accounting year. HMRC looks at your taxable turnover for any 12-month stretch, May to April, June to May, and so on. If that running total goes over £90,000, you have to register.

Taxable turnover is everything you sell that isn't VAT exempt or outside the scope of UK VAT. For a consultant, that normally includes:

Fees for consulting projects and advisory work
Retainers and service packages
Digital products and paid workshops, unless they are exempt

Services you buy from overseas businesses under the reverse charge also count towards your taxable turnover. If you pay for software, contractors or advertising from suppliers outside the UK, check how those costs affect your total.

What doesn't count is VAT exempt and out of scope income. Some education and training is exempt, but that exemption mostly applies to eligible bodies such as schools and universities, so a solo consultant's workshops and training are usually standard-rated. If you think any of your work is exempt, confirm it with HMRC guidance or an accountant before leaving it out of your total.

Mandatory and voluntary registration

You must register if you cross the threshold. You can also register voluntarily below it, which some consultants do because it can:

Make them look more established to larger clients, many of whom are VAT registered themselves
Let them reclaim VAT on eligible business expenses
Get the admin set up before growth forces it

The trade-off is that clients who aren't VAT registered, such as individuals and very small businesses, effectively pay more once you add VAT.

The two tests that force registration

1. The backward-looking test: the last 12 months

You must register if your taxable turnover for the last 12 months goes over £90,000. Total your last 12 months of invoices at the end of each month. If the figure is still under the line in July but tips over in August, August is the month that matters.

Deadline: you have 30 days from the end of the month in which you went over to register.

Effective date: your registration takes effect on the first day of the second month after you go over. From that date, you charge VAT.

GOV.UK's own example: if your turnover for the previous 12 months reaches £100,000 on 15 July, you must register by 30 August, and your effective date of registration is 1 September.

2. The forward-looking test: the next 30 days

You must also register if you expect your taxable turnover in the next 30 days alone to go over the threshold. This catches consultants who win a large project, a framework agreement, or several big retainers at once, even if their previous 12 months were well below the line.

Deadline: register by the end of that 30-day period.

Effective date: the date you realised you would go over, not the date your turnover crosses the threshold.

Where consultants get caught out

Irregular project income. One good quarter can spike your rolling total.
Large upfront retainers or deposits landing in a single month.
Overseas suppliers under the reverse charge, as above.

Special cases: overseas clients and more than one business

Overseas clients

UK VAT uses place of supply rules to decide where a service is taxed. For many business-to-business services to clients outside the UK, the service is outside the scope of UK VAT, which means it may not count towards your threshold either. The detail depends on where the client belongs and what you're supplying, so check HMRC's place of supply guidance or ask an accountant.

More than one business

If you're a sole trader, VAT registration covers you as a person, not each business you run. So turnover from a side project, a training brand and your main consulting practice is generally added together when you test the threshold. Separately, HMRC can combine businesses that have been split artificially to stay under the threshold. If you run more than one activity:

Keep clear records for each one
Note any shared clients, staff or resources
Raise the question directly with your accountant before you assume you're under the line

What to do once you need to register

Registering takes three steps:

Gather the key information: your business details, your turnover figures, and the date you went over or expect to go over the threshold
Register online with HMRC
Note your VAT registration number and your effective date of registration

From your effective date you charge VAT on taxable supplies, which affects:

Proposals and quotes, which should state whether prices include or exclude VAT
Contracts and retainers, which may need a clause covering VAT, especially for retainers agreed before you registered
Invoices, which must show your VAT number, the VAT rate and the VAT amount

You also need to keep digital VAT records and file VAT returns on time under Making Tax Digital, usually through accounting software.

How I handle VAT in Kiaro

Kiaro won't warn you when you near the threshold, because that calculation depends on what's exempt, out of scope or reverse-charged, and that's a judgement for you and your accountant. Kiaro keeps the invoice side consistent once you're registered and makes the numbers easy to pull.

VAT on every invoice. Add your VAT number in invoice settings and it prints on every invoice. Each client can have a default VAT rate, so their invoices pick up the right rate without you remembering it, and their VAT number prints in the Bill To block.
A turnover check in minutes. Export your invoices to CSV or Excel and you get the issue date, subtotal, tax and total for each one. Filter to the last 12 months, leave out drafts and voided invoices, and you have the starting figure for the backward-looking test.
Xero sync for your accountant. On the Solo and Team plans, every invoice you send pushes to Xero with its tax rate, so your VAT records and returns start from the same numbers.
Hours straight into invoices. Create an invoice from tracked time and each entry becomes a line item, so the net amount VAT is calculated on matches the work you did.

Put a monthly reminder in your calendar to run the 12-month total, and check GOV.UK for threshold changes whenever you do.