Last updated: 14 October 2026
What contracts and invoices do you need to avoid VAT problems?
You can’t legally “avoid” VAT that is due, but the right paperwork stops you paying VAT you don’t owe and protects your input tax claims. You need valid VAT invoices for every purchase you reclaim on, clear contracts that say whether prices include VAT, and evidence for any zero-rated, exempt, reverse-charge or outside-the-scope sale. Many VAT disputes come down to missing or unclear documents rather than the law itself.
What a full VAT invoice must show
- Your business name, address and VAT number
- A unique invoice number and the date of issue
- The tax point (time of supply), if different from the invoice date
- The customer’s name and address
- A description of the goods or services
- The quantity, unit price and rate of VAT for each line
- The total excluding VAT, the VAT amount and the total including VAT
Simplified invoices are allowed for retail sales of £250 or less including VAT.
Contract terms that matter
| Clause | Why it matters |
| “Prices exclude VAT” or “plus VAT” | Lets you add VAT if you become registered or the rate changes |
| Description of the supply | Supports the VAT rate you use, for example zero-rated construction |
| Place of performance and customer’s location | Supports outside-the-scope treatment for international services |
| Payment and deposit terms | Fix the tax point |
| Reverse charge statement | Required for construction services under the domestic reverse charge |
If a contract is silent, the price is usually treated as including VAT, which means you bear the VAT out of your margin.
Evidence for special VAT treatments
- Zero-rated exports: export declarations and proof of shipping
- Zero-rated new homes: planning permission and completion evidence
- 5% renovations: evidence the property was empty for 2 years or more
- Reverse charge: confirmation that the customer is VAT and CIS registered and not an end user
- Exempt supplies: a description that clearly matches the exemption
Example
A builder quotes £50,000 for a conversion. The contract doesn’t say “plus VAT”. HMRC later decides the work is standard-rated. Because the price is treated as VAT-inclusive, the builder must pay £8,333 VAT out of the £50,000 instead of charging the customer £60,000. A single clause would have protected him.
Purchase invoices
Before reclaiming VAT, check that the invoice is addressed to your business, shows a valid VAT number and is for a business purpose. Use HMRC’s online VAT number checker for new suppliers.
Keeping documents
Keep contracts, invoices and evidence for at least 6 years in digital form.
Invoices for deposits
If you take a deposit, issue a VAT invoice or receipt showing the VAT on it, because the deposit creates its own tax point.
Frequently asked questions
Can a contract make a supply exempt?
No. The VAT treatment depends on what is supplied, not on what the contract says.
Can I reclaim VAT with a pro-forma invoice?
No. You need a proper VAT invoice.
What happens if a supplier isn’t VAT registered but charges VAT?
You can’t reclaim it. Ask for a corrected invoice.
Are electronic invoices valid?
Yes, if your customer agrees and the invoice has all the details.
Related: checking your supplier’s VAT number and issuing a VAT invoice for expenses.
Talk to Accotax
Want this handled for you? Our team at Accotax can help with VAT-compliant contracts and invoices. See our VAT accountants service, or contact us for a free, no-obligation quote.
This page is general guidance based on HMRC rules for the 2026/27 tax year, checked against gov.uk on 14 October 2026. It is not personal advice, so speak to an accountant about your own situation.
