Medius and Avalara Partner to Automate US Sales Tax Verification in AP Workflows

Medius has integrated Avalara AvaTax into its accounts payable automation platform to enable real-time US sales and use tax verification during the invoice approval workflow. For fintech professionals, this shift moves tax determination upstream, allowing businesses to identify overcharges and undercharges before funds leave the company or data hits the ERP, reducing costly recovery exercises.

What was announced

The integration connects Avalara AvaTax indirect tax determination directly with Medius AP Automation. This allows finance teams to verify vendor-charged US sales and use tax on every invoice line by line, across thousands of jurisdictions, without leaving their primary approval interface. As invoices move through the Medius workflow, the system automatically recalculates taxes against Avalara’s determination service. Any discrepancies—whether overcharges that drain cash or undercharges that create use-tax liabilities—are flagged for review before the payment is executed or the record is posted to the ERP.

This move addresses a specific friction point in financial operations: the timing of tax checks. Historically, many businesses have performed tax determination after payment, necessitating manual recovery efforts for errors. The new connectivity is designed for the more than 250 mutual customers already using both platforms, providing them with a way to apply existing tax logic within their daily AP processes. Because the verification is embedded, it removes the need for a separate platform or manual review steps that typically slow down the approval cycle.

Medius is showcasing the integration at the Avalara CRUSH 2026 event in Fort Lauderdale through September 24. The company has emphasized that this integration is part of a broader strategy of financial compliance extensibility, following a similar integration with Thomson Reuters ONESOURCE earlier this month. The platform utilizes an open set of APIs to allow third-party systems to plug into the AP workflow, with additional integrations expected to follow in the tax and compliance space.

"Most of our customers settled the question of which tax engine to run years ago. What they haven't solved is timing. The determination is accurate, but it arrives after the invoice has been approved and paid, which turns every correction into a recovery exercise. We moved the check upstream, into the approval step. It is a small change in sequence and a large change in what it costs to get tax wrong."

Gary Hall, Chief Product Officer, Medius.

The companies involved

Medius is a prominent provider of accounts payable automation and spend management solutions. The company focuses on streamlining the entire invoice-to-pay process, helping finance departments gain control over their spending and improve operational efficiency. With a significant presence in the global market, Medius has established itself as a key player for mid-market and enterprise organizations looking to digitize their back-office financial functions through automation and AI-driven workflows.

Avalara is a leader in cloud-based tax compliance automation. Its flagship product, AvaTax, is designed to handle the complexities of indirect tax, including sales and use tax, VAT, and GST, across various global jurisdictions. Avalara’s platform integrates with a wide range of ERP, e-commerce, and billing systems, providing real-time tax calculations and automated filing services. The company has a long history of helping businesses navigate the shifting landscape of tax regulations, which currently span thousands of local and state jurisdictions in the United States alone. Together, the two companies serve a substantial overlapping customer base, reflecting their shared position as essential infrastructure for modern, automated finance departments.

What FF News has reported before

FF News has closely followed the expansion of both companies within the fintech ecosystem. Recently, Medius has focused on scaling its international operations, including the appointment of Medius Names Maartje van Zadelhoff as Sales Director to Scale Benelux Operations. The company also recently highlighted internal risks in the sector through its Medius Financial Census: 87% of Finance Professionals Admit to Ignoring Small-Scale Fraud.

Avalara has similarly been active in expanding its reach, particularly in the small business sector, as seen when Avalara Automates Sales Tax Compliance for QuickBooks Businesses. Furthermore, FF News covered the company’s research into emerging technologies, reporting that Australian Finance Leaders Prioritize Speed Over Governance in AI Agent Race, Avalara Survey Finds.

What this means

This integration signals a shift in the AP automation market from simple workflow management toward deep, real-time compliance. By moving tax determination "upstream," Medius and Avalara are putting pressure on legacy ERP systems and standalone AP tools that treat tax as a post-payment reconciliation task. In an era of tightening margins and aggressive state-level tax enforcement in the US, the cost of "paying now and fixing later" is becoming unsustainable for many firms. The industry is moving toward a model where the invoice approval process acts as a final, automated gatekeeper for both regulatory compliance and cash preservation, making interoperability between tax engines and AP platforms a baseline requirement.