Business-to-business (B2B) e-invoicing is voluntary in Switzerland, though it’s strongly encouraged by the Swiss government for its efficiency and alignment with European initiatives like VAT in the Digital Age (ViDA). Recommended formats include swissDIGIN, UBL XML, CII, ZUGFeRD/Factur‑X, and Peppol BIS. If choosing to issue e-invoices, businesses must guarantee integrity, authenticity, and inalterability with electronic signatures under the Swiss e‑Signatures Act (ZertES). As with B2G transactions, B2B e-invoices must be archived for 10 years.