E-invoicing guides

What applies from 2027 and 2028 and how to open, validate and create e-invoices. Every legal statement names its official source; the guides are not tax advice.

• E-invoicing mandate 2027 and 2028: deadlines and exceptions
• Open and read an XRechnung
• Validate an XRechnung
• Receive e-invoices
• Create an e-invoice for free
• Create a ZUGFeRD invoice
• XRechnung or ZUGFeRD?
• Leitweg-ID: invoices to public authorities
• E-invoicing API for software vendors
• E-invoices for Shopify and WooCommerce