1. Set the 1–7 September scope, ownership and decision rights
Define the command centre as a temporary operating model for 1–7 September 2026, not as a substitute for normal AP, AR, tax or IT governance. Start with a legal-entity and flow matrix: SIREN and relevant SIRET, issuing and receiving populations, domestic B2B e-invoicing, transactions subject to e-reporting, payment-data flows where applicable, PA connection, ERP or accounting system, invoice format such as Factur-X, UBL or CII, and the business owner of each flow. Include volumes and criticality, but do not mix entities merely because they share an ERP. A routing defect affecting one establishment should remain traceable to that establishment and its invoices. Assign an incident commander, PA liaison, ERP/integration lead, AP lead, AR lead, tax or compliance reviewer, treasury/payment-control owner and communications owner. The commander prioritises and records decisions; specialists diagnose and execute. Give explicit decision rights for pausing an interface, releasing a corrected batch, sending an incident continuity copy, contacting a customer, and accepting recovery totals. Require two-person approval for actions that could create a second payable, posting or report. Publish one rota and one escalation tree, including out-of-hours contacts and contractual PA support channels. These are recommended internal controls, not DGFiP-prescribed roles or official response times. The legal start dates remain applicable: launch pragmatism is neither a grace period nor a safe harbour. Verify current official guidance, contracts and entity-specific tax and accounting treatment before go-live.