Magento's native tax engine relies on manually maintained tax rates and rules, which collapses the moment you sell into thousands of US tax jurisdictions with shifting rates, special districts, and product-specific taxability. This extension replaces that with live Avalara AvaTax determination so the tax your customer sees at checkout is the tax you remit.

ECOSIRE builds this as a custom Magento 2 module under app/code/Ecosire/AvataxConnector, implementing Magento's tax service contracts and registering an interceptor (plugin) on the tax calculation flow so AvaTax rate calls run during quote totals collection. Calls are routed through Avalara's REST API using credentials stored via Magento's encrypted system configuration, with admin ACL gating access to settings and logs. Address validation runs at checkout and in the customer address book against Avalara's 13,000+ US jurisdiction database, normalizing addresses before tax is computed.

Exemption handling integrates Avalara CertCapture so tax-exempt customers and B2B accounts carry the right exemption codes. Product tax codes and nexus are configured per your catalog and where you have obligations, and committed transactions are pushed to AvaTax to feed automated returns filing (the filing itself remains in Avalara's platform — we wire the handoff, not the filing license).

Because every store differs — custom checkout, headless/GraphQL frontends, multi-store, multi-currency, Adobe Commerce B2B — this is scoped, built, and installed on your environment, not a one-click Marketplace download. You get clean, upgrade-safe code (DI, plugins, observers — no core hacks), a staging install, UAT against real orders, and production cutover. An active Avalara AvaTax subscription and API credentials are required.