[FEATURE] - Support for German E-Invoice Standards (ZUGFeRD & XRechnung)

[burnziii]

Feature Summary

Support for German electronic invoice standards such as ZUGFeRD and XRechnung, enabling export of invoices in standardized, legally compliant formats.

Use Case

In Germany, electronic invoices to public authorities (B2G) must comply with XRechnung, while many businesses prefer the hybrid ZUGFeRD format for B2B transactions. This feature would allow users to generate and submit invoices that meet German legal and regulatory requirements, significantly increasing invoify’s adoption in the DACH region.

Proposed Solution
• Add an export option for invoices as ZUGFeRD-compliant PDF with embedded XML (preferably ZUGFeRD 2.1.1 or higher).
• Add support for exporting invoices as XRechnung XML.
• Provide a configuration option in the UI to choose the desired invoice standard (ZUGFeRD or XRechnung).
• Allow selection of ZUGFeRD profiles (e.g., BASIC, COMFORT, EXTENDED, EN16931).

Additional Information
• ZUGFeRD and XRechnung are based on the EN 16931 European standard and are widely used in Germany and Austria.
• Open-source libraries for ZUGFeRD/XRechnung already exist (e.g., mustangproject), which may simplify implementation.
• These formats will soon be mandatory for B2B invoicing under upcoming EU regulations (ViDA initiative), making early support a strategic benefit for invoify.