Does Your VAT Invoice Meet the Legal Requirements?

Every VAT-registered business knows the basics: put your VAT number on the invoice, show the tax amount, include dates. Most compliance guides stop there, listing the standard fields and moving on.

The invoices that fail audit checks rarely fail on the obvious fields. They fail on conditional requirements: the reverse charge wording that was never added, the directors' names that triggered a rule nobody knew about, the foreign currency amount that was never converted. These are the VAT invoice requirements that only apply in specific circumstances, and they are the ones most likely to be missing.

A VAT invoice is not a receipt. A receipt acknowledges payment. A VAT invoice is evidence that a taxable transaction took place, and it is the primary document your customer needs to reclaim input tax. If the invoice is incomplete, their claim gets blocked. The consequences land on both sides.

Under EU rules, an invoice is required for most business-to-business supplies and for certain B2C transactions. The UK follows a parallel structure with its own specifics.

Mandatory fields: UK full VAT invoice

A full UK VAT invoice must include:

• Invoice date
• Unique sequential identification number
• Supplier’s name, address, VAT registration number, and contact details
• Customer’s name and address (and VAT registration number where applicable)
• Description of the goods or services
• Quantity supplied
• Date of supply
• Unit price excluding VAT
• Net amount
• VAT rate charged
• Total VAT amount
• Total amount payable including VAT

A full VAT invoice must be issued for supplies where the total amount payable, including VAT, is more than £250. That threshold is VAT-inclusive, not net.

Mandatory fields: EU full VAT invoice

The EU full invoice shares many of the same fields but has its own specific list:

• Date of issue
• Unique sequential number
• Supplier’s full name, address, and VAT identification number
• Customer’s full name, address, and VAT identification number (where the customer is liable for tax)
• Description and quantity of goods or services supplied
• Unit price exclusive of tax, discounts, or rebates (unless included in the unit price)
• Date of transaction or payment (if different from invoice date)
• VAT rate applied and amount payable
• Breakdown of VAT amount payable by VAT rate or exemption

Simplified VAT invoices: what they must still carry

Below the £250 threshold in the UK, a simplified invoice is permitted. Under EU rules, a simplified VAT invoice must include:

• Date of issue
• Supplier’s VAT identification number
• Type of goods or services supplied
• VAT amount payable (or the information needed to calculate it)

The simplified format is common in retail. But “simplified” does not mean “optional.” Missing any of these fields invalidates the invoice for input tax purposes.

Conditional requirements that catch businesses out

This is where most VAT invoices go wrong. The core fields above are table stakes. The following requirements only activate in specific circumstances, and omitting them when they apply makes the invoice non-compliant.

Reverse charge

When the customer is liable for VAT rather than the supplier (the reverse charge procedure), the invoice must include the words “reverse charge”. No alternative phrasing. No footnote reference. The literal words “reverse charge” must appear on the document.

Self-billing

Where the customer issues the invoice on behalf of the supplier, the invoice must carry the words “self-billing”. Businesses can outsource invoicing to a third party or to the customer under EU rules, but only with the correct designation on the document.

Cash accounting (EU)

Under EU rules, suppliers operating a cash accounting system must include the words “cash accounting” on their invoices.

Exempt transactions

For exempt supplies, the invoice must include a reference to the relevant EU or national legislation, or any other reference indicating that the supply is exempt. The choice of format sits with the supplier.

Supplier identity rules: sole traders vs limited companies

The supplier details on a VAT invoice are not a simple “name and address” field. The rules vary by business structure.

A sole trader must show their name and any business name being used. When trading under a business name, the invoice must also include an address where legal documents can be delivered to the supplier.

For limited companies, the invoice must show the full company name exactly as it appears on the certificate of incorporation. And there is a lesser-known rule: if the company decides to put the names of its directors on VAT invoices, it must include the names of all directors.

Foreign currency and cross-border invoices

VAT invoices can be issued in a foreign currency, but with a constraint. For supplies taking place in the UK, the total VAT payable must be converted to British Pounds. The line items and net amounts can stay in the original currency. The VAT total cannot.

For cross-border transactions within the EU, electronic invoices are legally equivalent to paper invoices, subject to acceptance by the recipient. For B2G transactions specifically, public administrations in the EU must accept structured electronic invoices.

If your business invoices across multiple currencies regularly, building the conversion into your invoice template saves time. Our VAT invoice template includes fields for both the original currency and the GBP-converted VAT total.

When no VAT invoice is required

Not every B2B transaction needs a VAT invoice. UK rules provide the following exemptions:

• The customer operates a self-billing scheme or the supplier issues certified receipts
• The supply is a gift of goods on which VAT is chargeable
• The supply falls under one of the VAT second-hand margin schemes
• The invoice is only for exempt or zero-rated sales within the UK

These exemptions are narrow. If you are unsure whether your transaction qualifies, issue the invoice. An unnecessary VAT invoice causes no compliance problem. A missing one does.

Record keeping and issuance deadlines

Two timing rules apply to every VAT invoice.

First, you must normally issue a VAT invoice within 30 days. Late issuance can delay your customer's ability to reclaim input tax.

Second, you must keep all your business records for VAT purposes for at least 6 years. The VAT invoices you receive are your primary evidence for reclaiming input tax, so organised storage matters.

One important protection: once a VAT invoice contains all required information, no EU Member State can deny the right to deduct VAT by demanding extra information beyond what the rules specify. If your invoice is complete, the deduction stands.

Getting compliance right at scale

The core VAT invoice requirements are straightforward. The conditional rules are where compliance breaks down, because they only matter for specific transaction types and are easy to overlook in a template built for standard domestic sales.

If you process invoices from multiple vendors across different transaction types, catching these conditional fields manually is a volume problem. Zerentry's AI extraction pulls every field from each document, including the conditional wording requirements, and returns a confidence score so incomplete invoices surface before they turn into a rejected input tax claim months later during an audit.

For businesses handling e-invoicing transitions alongside existing VAT compliance, the field requirements overlap but are not identical. Getting the VAT invoice right remains the foundation.

VAT invoice FAQ