Microsoft Dynamics 365 Business Central ships solid native tax setup — Tax Groups, Tax Areas, VAT Posting Groups and VAT Business/Product Posting Group combinations — but it expects you to maintain every rate, every jurisdiction boundary and every exemption rule by hand. As soon as you sell across US states, EU member states, the UK, the GCC or APAC GST regimes, that manual matrix becomes a compliance liability.

This is a build-to-order AL extension that brings Avalara-style automated tax determination directly into Business Central. ECOSIRE designs, builds, installs and supports it on your tenant — it is not an instant Microsoft AppSource download. We scope your jurisdictions and connected tax-content provider, develop the extension, deploy it as a per-tenant extension (or submit through AppSource if you require it), then support and update it.

The engine subscribes to standard sales and purchase document events (table and page extensions over Sales Line, Purchase Line, and the posting routines via OnAfterValidateEvent and posting OnBefore event subscribers). On line entry it calls your tax-content gateway, resolves the correct jurisdiction from a cleansed ship-to/ship-from address, applies the right rate and exemption logic, and writes the result back to the document and the posted VAT/tax entries — no rip-and-replace of native posting.

Address validation, product tax categories, exemption-certificate storage, and nexus/threshold tracking are all surfaced on native-feeling pages with their own permission sets. Tax calls run inline for accuracy and can be batched via the Job Queue for high-volume documents. Because it's your tenant's own extension, you keep full control, an audit trail, and a documented upgrade path across BC monthly releases.