The key elements determining the legal compliance of electronic invoicing are:
Authenticity of origin - based on the use of electronic signatures or based on the exchange of invoices in electronic form
Integrity of the content - guarantee of the immutability of the content of the document from the moment of issuing the invoice to archiving
Readability – providing a human-readable view even when they are exchanged in a structured format (XML or UBL)
Storage - time of archiving and, if applicable, place of archiving