1. Set the decision unit before judging readiness
Do not issue one verdict for a group, programme or ERP unless every relevant legal entity and flow has the same evidence. The practical decision unit is a legal entity identified by SIREN, then divided where necessary by invoice direction, operational perimeter and reporting lane. Record inbound purchasing, outbound sales, transaction e-reporting and payment-data reporting separately. Add establishments or SIRETs when they affect routing, permissions or operational ownership, but do not confuse an establishment-level test with proof for the legal entity as a whole. Start with a scope sheet containing the legal name, SIREN, relevant SIRETs, VAT position, size category, PA, source systems, AP and AR owners, receiving addresses, customer and supplier populations, and the flows expected at launch. The legal timetable must be explicit: on 1 September 2026 all affected businesses must be able to receive electronic invoices. Large enterprises and ETIs also start issuing electronic invoices and e-reporting on that date; SMEs and micro-enterprises start issuing and e-reporting on 1 September 2027. Confirm classification and tax scope against current official material or qualified advice where facts are unusual. A shared platform does not justify a shared verdict. One subsidiary may have valid directory routing and a successful inbound trace while another has an unresolved SIREN mapping. Likewise, an entity can be ready to receive yet not ready for an in-scope outbound or e-reporting lane. The decision sheet should therefore show one row per entity-and-flow combination, with a consolidated group view produced only after those rows are decided. A project percentage, a generic vendor assurance or a test completed for a sister company is insufficient because none identifies the accountable taxpayer, direction and lane actually being approved.