How to Check a Builder’s VAT Registration in 2026 (UK)
You can verify any builder’s VAT number for free in under a minute using HMRC’s official “Check a UK VAT number” service. A valid UK VAT number is “GB” followed by 9 digits. Businesses must register once taxable turnover passes the £90,000 threshold — so a small builder legitimately may not be registered, but one charging “VAT” without a valid number is a red flag.
How to check a builder’s VAT registration step by step
Whether a builder is VAT-registered affects your price and tells you something about the size and legitimacy of the business. Here’s how to verify it properly when comparing quotes.
1. Ask the builder for their VAT number
A VAT-registered builder must show their VAT number on quotes and invoices. Ask for it up front — a genuine business will provide it without hesitation.
2. Verify it with HMRC’s free online checker
Use the government’s official “Check a UK VAT number” service at gov.uk/check-uk-vat-number. Enter the number and it confirms whether it’s valid and shows the registered business name and address. It’s free and takes seconds. For businesses trading in the EU you can cross-check on the EU VIES service.
3. Check the number format
A standard UK VAT number is “GB” plus 9 digits (for example GB 123 4567 89). If the format is wrong, or it fails the HMRC checker, treat any VAT being charged as suspect.
4. Confirm invoices display the VAT number
Every VAT invoice must show the supplier’s VAT number, the VAT rate and the VAT amount as a separate line. Cross-check the number on the invoice against what the HMRC checker returned, and make sure the registered name matches the business you hired.
Why VAT registration matters when comparing quotes
The VAT registration threshold in 2026 is £90,000 of taxable turnover (raised from £85,000 in April 2024). A builder below that threshold is not required to register and cannot legally add VAT — which is why a smaller sole trader’s quote can look 20% cheaper than a larger firm’s for the same work. A larger, VAT-registered contractor adds 20% VAT, but is typically a more established business. If you are VAT-registered yourself, a valid VAT invoice lets you reclaim the VAT. Some building work is zero-rated or reduced-rated whatever the builder’s size — for example, check whether a tarmac driveway is VAT-free before you assume 20% applies.
Red flags to watch for
Be cautious if a builder charges “VAT” but won’t provide a number, gives a number that fails the HMRC checker, or whose registered name doesn’t match the trading name. Charging VAT without being registered is a form of fraud — you’d be paying “VAT” that never reaches HMRC. Alongside the VAT check, verify the builder on Companies House, confirm membership of FMB or TrustMark, and ask to see public-liability insurance. It also pays to read the builder’s quote closely so any VAT assumption is itemised before you commit.
Using HMRC’s “Check a UK VAT number” service in practice
The official checker is free, needs no login and returns an answer in seconds — but it only works if you already have the number. You cannot search HMRC’s service by business name, so always ask the builder for the number first. Open the GOV.UK “Check a UK VAT number” service, type in the “GB” number (spaces are ignored) and press check. It confirms whether the number is valid and, for most registrations, shows the registered business name and address so you can match it to the firm that quoted you. If you want proof for your own records, choose the option to enter your own VAT number and HMRC returns a dated reference showing you carried out the check.
What a valid VAT invoice must show
A proper VAT invoice is more than a number on a letterhead. It must set out the supplier’s name and address, their VAT registration number, a unique invoice number and the date, a description of the work, the amount charged before VAT, the VAT rate applied (the standard rate is 20%) and the VAT shown as a separate line. If any of those are missing you cannot reclaim the VAT, and it is worth querying before you pay. Our companion guide on builder invoices and VAT walks through a fair bill line by line.
What to do if a “VAT” charge looks wrong
If a quote adds 20% “VAT” but the builder cannot give you a number that passes the checker, pause. Ask them to confirm the registration in writing and re-run the number. A mismatch between the trading name and the registered name, or a refusal to itemise the VAT, are both reasons to walk away — and to check the written contract before any money changes hands. If you have already paid and later suspect the VAT was never legitimate, keep every invoice and report it to HMRC: charging VAT without being registered is fraud, not an administrative slip.
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