What has to be on an invoice in the EU

An invoice is not a receipt with a logo on it. In the EU it is the document that entitles your business customer to deduct the VAT they paid you, and its content is prescribed by law. An invoice missing a required particular can have that deduction refused, which turns your paperwork problem into your customer's cash problem — and that is a reliable way to lose a trade account.

The required particulars

Article 226 sets out what a full VAT invoice must show. In practice that is:

• Date of issue.
• A sequential number, based on one or more series, uniquely identifying the invoice.
• Your VAT identification number.
• The customer's VAT identification number, where the customer is liable for the tax on the supply or where goods are supplied intra-Community.
• Full name and address of both supplier and customer.
• Quantity and nature of the goods supplied, or the extent and nature of the services.
• Date of supply or completion — or the date of a payment on account — where that differs from the date of issue.
• Taxable amount per rate or exemption, the unit price excluding VAT, and any discounts or rebates not already reflected in the unit price.
• The VAT rate applied.
• The VAT amount payable, unless a special arrangement excludes it.
• A reference to the relevant provision where the supply is exempt or the customer is liable — in practice, wording indicating exemption or reverse charge.
• The required wording for special schemes, such as "Cash accounting", "Self-billing", "Reverse charge", or the applicable margin-scheme mention.

Two of these cause most of the trouble. The date of supply is routinely omitted when it differs from the invoice date, which matters because the supply date usually determines the VAT period. And the customer's VAT number is frequently missing on intra-Community supplies, where it is a substantive condition for zero-rating rather than a formality — get it wrong and the supply may be treated as domestic, with the VAT payable by you.

Simplified invoices

For small amounts the Directive allows a reduced set of particulars. The baseline threshold is EUR 100, and Member States may permit simplified invoices up to EUR 400, or where trade practice makes a full invoice impractical.

A simplified invoice must still show:

• The date of issue
• Identification of the supplier
• Identification of the goods or services supplied
• The VAT amount payable, or the information needed to calculate it

Simplified invoices cannot be used for intra-Community supplies or for cross-border supplies where the customer is liable for the tax. If you sell to consumers at retail and to businesses cross-border, you need both document types — which is a reason to have the format follow from the transaction rather than from which template someone opened.

Numbering

The requirement is a sequential number, from one or more series, that uniquely identifies the invoice. Several practical consequences follow:

• Multiple series are allowed. INV-2026-0001 alongside CN-2026-0001 for credit notes, or separate series per location, is fine — provided each series is internally sequential.
• No gaps within a series. A gap invites a question at audit. If a document is cancelled, keep the number and mark it cancelled rather than deleting it and closing the gap.
• No reuse, ever. Including across years, unless your series explicitly incorporates the year.
• Assign at issue, not at draft. Numbering drafts is how gaps appear.

This is one of the clearest arguments against invoicing from a word processor or spreadsheet. Sequence integrity is a property a system can guarantee and a person cannot — a duplicated number from a copied template, or a gap from a deleted file, is invisible until someone asks about it a year later.

Corrections and credit notes

Once issued, an invoice is not edited. A document that amends an earlier invoice is itself treated as an invoice and must carry a specific and unambiguous reference to the original.

• Credit note — reduces the original: returns, discounts agreed after issue, overcharges, cancellations.
• Debit note — increases it, where an undercharge needs correcting.

Both need their own sequential number, the reference to the original invoice, and the same particulars as the document they amend. Correcting by reissuing an invoice under the same number, or by editing a PDF, breaks the audit trail — and if the original has already been reported on a VAT return, it also misstates the return.

Keep the reason with the credit note. "Damaged in transit, 12 units" takes seconds to record and answers the question that would otherwise take an afternoon to reconstruct. Credit notes are also a genuinely useful management signal: a rising credit-note ratio usually indicates a quality, packing, or expectation-setting problem well before it shows up in returns data.

Deadlines and storage

For intra-Community supplies of goods, and for cross-border B2B services where the customer accounts for the tax under the reverse charge, the invoice must be issued by the fifteenth day of the month following the month in which the chargeable event occurred. Domestic deadlines are set nationally and are often tighter than businesses assume.

Retention periods are also set by Member States, commonly between six and ten years. The requirements that apply throughout the retention period are authenticity of origin, integrity of content, and legibility. Electronic storage is permitted; the practical implications are that you keep the issued document rather than the ability to regenerate it, that a stored invoice must not be alterable after the fact, and that you must be able to produce it on request within the whole period.

What is changing

Structured electronic invoicing is moving from optional to mandatory across the EU. Business-to-government e-invoicing has been required since Directive 2014/55/EU. Under the VAT in the Digital Age package, structured e-invoicing and digital reporting for intra-EU transactions are being phased in toward the end of the decade, and several Member States are running their own domestic mandates on earlier timetables.

The practical point for a small business is the direction, not the dates: invoices are becoming structured data rather than documents. A PDF that a human reads is increasingly not the deliverable. Systems that already hold invoice data as fields — rather than as text laid out on a page — will adapt to a national mandate by adding an export format. A folder of PDFs will need rebuilding. Check your own country's timetable, because national dates vary considerably.

A practical checklist

• Both parties' full legal names and addresses, and your VAT number on every invoice
• Customer's VAT number on every intra-Community supply, validated before zero-rating
• Sequential number from a defined series, assigned at issue, never reused
• Supply date shown whenever it differs from the issue date
• Taxable amount and VAT shown separately for each rate
• Required wording present for exemption, reverse charge, or margin schemes
• Corrections made by credit or debit note referencing the original, never by editing
• Documents stored unaltered for the national retention period

None of this is difficult once it is set up. It is difficult when every invoice is a copy of the last one, which is precisely how the wrong VAT rate, a stale address, or a duplicated number ends up on a document you are legally required to keep for a decade. The related mechanics of rates, thresholds, and returns are covered in VAT basics for small product businesses.