Zero-downtime tax migration — Avalara to Vertex

The challenge

Avalara tax exemption license was expiring, posing critical compliance and operational risk. All quote, order, and tax validation processes dependent on Avalara. Risk of billion-dollar revenue delays and compliance breaches with only weeks to implement.

System complexity

This was a high-stakes, time-critical engagement for a $1.6B cloud contact center company (believed to be Genesys). The Avalara tax exemption license was expiring with only weeks to implement a replacement. All quote, order, and tax validation processes across 150+ users in Sales, Finance, and Tax departments depended on the existing integration.

The architectural challenge: build a modular integration that could switch between tax providers without code changes, handle automated certificate retrieval and validation, parse complex XML tax responses, and maintain zero downtime during the transition — all while processing billions in annual revenue through the system.

What we built

• Modular Vertex API integration using Named & External Credentials
• Configuration-based toggle enabling instant switch between Avalara and Vertex with zero code changes
• Automated certificate retrieval, validation, and upsertion with Apex services
• Zero-disruption transition compatible with existing Quote workflows

The outcome

• Zero downtime — seamless transition unnoticed by users
• Validation time: 2-3 days → less than 5 seconds
• >95% accuracy
• Eliminated dependency on expiring vendor licenses

Technologies: Salesforce Revenue Cloud, Vertex API, Apex