Rechnungsnummer

Rechnungsnummer is the unique identifier assigned to each invoice by the issuer. It serves as a reference for both the seller and the buyer, and it supports bookkeeping, payment matching, and tax reporting. The number helps prevent confusion between invoices and provides an auditable trail for accounting and authorities.

Format and generation of a Rechnungsnummer vary by country and company policy. Common approaches use a fortlaufende Nummerierung (continuous sequential numbering) or a structured code that may incorporate the year, department, or customer identifier. Invoices may be alphanumeric and can include separators or prefixes, but the crucial requirement is uniqueness. A single invoice number should never be reused, even if an invoice is cancelled or corrected; the corresponding credit note typically receives its own invoice number.

Regulatory context and best practices differ by jurisdiction but share core principles. In Germany, invoicing rules are tied to the Umsatzsteuergesetz (UStG) and the GoBD standards for proper bookkeeping, which emphasize a unique, traceable and complete sequence of invoice numbers. Similar expectations exist in Austria and other German-speaking regions, where the invoice number is used to ensure auditability and accurate VAT reporting. While some laws require a consecutive sequence, many regimes simply require uniqueness and non-repetition, with exact formal requirements varying by country.

Practical guidance for businesses includes adopting a consistent numbering scheme, using software to automate generation, and documenting the policy to avoid reuse or gaps that could complicate audits. The Rechnungsnummer is a small, but essential, part of compliant invoicing and reliable financial records.