This is a build-to-order Business Central extension, not an instant AppSource download. ECOSIRE builds it in AL, installs it as a per-tenant extension on your Business Central environment (SaaS Online or on-prem), and supports it after go-live.

The connector wires Avalara's AvaTax determination engine directly into the BC posting pipeline. Using AL event subscribers on the sales and purchase posting codeunits (OnBeforePostSalesDoc, OnAfterReleaseSalesDoc and related publishers), it intercepts documents before they post, builds an AvaTax CreateTransaction payload from the document lines, ship-from/ship-to addresses and tax codes, and writes the returned line-level tax back onto the document — so the GL, customer ledger and VAT entries reflect Avalara's real-time rate determination across 75+ countries (US/Canada sales & use tax, EU/UK VAT, GST and more).

We add table and page extensions for AvaTax tax codes, entity-use (exemption) codes and nexus/registration mapping, a setup page holding the AvaTax account ID, license key and company code (license stored via BC's isolated storage), and a permission set scoping who can post and reconcile tax. Address validation runs against Avalara's address API on customer/vendor cards. Calls are made through BC's HTTP client to the AvaTax REST endpoint, with a job queue entry for retry, batch commit (commit/void on posting and credit) and return-file data export.

Because it is your own per-tenant extension, the source is yours, it survives BC major upgrades (we recompile against each release), and there is no shared multi-tenant black box. You bring the Avalara account; we deliver the certified-pattern integration, deploy it, and validate it against real posting scenarios in a sandbox before production cutover.