Denmark has officially cancelled OIOUBL 3.0, replacing it with the new NemHandel BIS 4 standard, which will begin a phased rollout in 2028 before fully replacing OIOUBL 2.1 by mid-2029. Until this transition, OIOUBL 2.1 remains the active standard for B2G and voluntary B2B exchange. Businesses invoicing the public sector must continue using the EAN (GLN) number to ensure correct invoice routing, while the Danish Bookkeeping Act strictly mandates the digital archiving of all accounting records and supporting documentation for five years.