Belgian finance teams face a structural change, not a formatting change. Structured electronic invoicing between Belgian VAT-registered businesses means an invoice is no longer a PDF you email — it is a UBL document that must be addressed to a registered Peppol participant, validated against the Peppol BIS Billing 3.0 rules, transmitted through a certified access point, and provable years later. Dynamics 365 Business Central ships genuine electronic-document plumbing — the E-Document framework, the Service Participant and electronic-document service setup, PEPPOL export codeunits and the standard PEPPOL BIS Billing 3.0 format — but it stops short of a Belgian production process. There is no participant lookup against the Peppol directory before you post, no Belgian VAT-category mapping that survives reverse charge and intra-community supply, no queue that tells an AP clerk which invoices were rejected by the receiver's access point and what to do about them, and no archive whose retention story a Belgian auditor will accept without a spreadsheet.

We build a Business Central AL extension that closes that gap end to end. On the posting side, table extensions on Customer carry the Peppol participant identifier (typically the 0208 Belgian enterprise-number scheme) and the endpoint scheme code, with a lookup codeunit that resolves and caches the participant against the SML/SMP so a bad identifier is caught at order entry rather than at transmission. A VAT Posting Setup extension maps each Belgian VAT combination to its UNCL5305 tax category and, where required, the exemption reason code and text — so posting a Sales Invoice Header produces a UBL that carries S, AE, K or E correctly rather than a hardcoded standard rate. Event subscribers on OnAfterPostSalesDoc enqueue the posted document; a job queue entry drives the transmission codeunit, which serialises the UBL via the extended PEPPOL mapping, submits it to your access point over its REST or AS4 interface, and records the transmission ID, timestamp and receiver acknowledgement on a new Peppol Transmission Log table. The same posting produces the human-readable PDF from your existing report layout, so the customer-facing document and the machine document never drift apart.

Rejections are treated as a first-class workflow, because in practice that is where the effort goes. A message-level rejection (schematron failure, unknown participant, unroutable document type) or a business-level rejection returned by the receiver lands on a Peppol Rejections list page with the raw reason, the mapped plain-language cause, and a prescribed action: fix and resubmit, or issue a credit memo and reissue. The extension refuses to silently overwrite a transmitted document — a corrected invoice is a new document with a documented relationship to the original, which is what keeps the audit trail defensible. Archiving stores the exact transmitted UBL byte-for-byte alongside the acknowledgement, so what you can produce in year seven is what actually left your tenant, not a regenerated approximation.

Everything is exposed for the systems around Business Central. API pages published under a dedicated API group expose the transmission log and rejection queue over OData v4 / REST API v2.0, so a Power Automate flow, a Dataverse-connected Power App or your finance data warehouse can read status without touching the AL layer. Permission sets separate the AP clerk who resubmits from the administrator who configures access-point credentials, and those credentials live in isolated storage rather than in a visible setup field. The extension targets current Business Central release waves and is built as a per-tenant extension for SaaS by default; an on-premises build is available where your deployment requires it.

This is build-to-order, and we are explicit about what that means. There is no instant download and this is not an existing AppSource listing. You request a quotation, we run a scoping call to establish your Business Central version and deployment type, your access-point provider, your Belgian VAT scenarios and the shape of your existing sales documents, and then we build the extension against that scope. Typical delivery is one working week from confirmed scope. You receive the installable app plus the full AL source for your version, installation and configuration on your environment, UAT on a sandbox with a documented rollback plan, technical and end-user documentation, a training session for your finance team, and a post-go-live support window. Choice of access point stays yours — we integrate with the provider you have contracted, we do not resell one.