Invoice Compliance: Legal Requirements, Retention & E-Invoicing
Invoicing is regulated. What an invoice must contain, how long you must keep it, and — increasingly — the technical format it must be issued in are all set by law, and the law is moving fast: a growing list of countries now mandates structured e-invoicing for business-to-business sales.
These guides map the landscape. They are educational, not legal advice, and where a rule is national they say which country sets it rather than pretending one answer fits everyone.
Rules in this area are set nationally — they differ by country and change over time. These guides are educational, not legal or tax advice.
All 5 Guides
- E-Invoicing Mandates: Who Must Switch, Where, and WhenStructured e-invoicing is becoming law across the EU and beyond. The map and the timeline.Read the guide
- What Makes an Invoice Legally Valid?The fields the law cares about, and how requirements differ by country.Read the guide
- How Long to Keep Invoices: Retention Rules by PurposeTax audits, warranties and disputes each set their own clock. Keep the longest one.Read the guide
- Electronic Signatures on Business DocumentsSimple, advanced and qualified signatures — and whether invoices need one at all.Read the guide
- Peppol: The Network Behind Modern E-InvoicingHow Peppol moves structured invoices between businesses, and who has to use it.Read the guide