Vertex Indirect Tax O Series integrates with an ERP, billing system, or ecommerce platform to deliver accurate tax determination on every sales and purchase transaction. Vertex Indirect Tax O Series is a robust indirect tax calculation engine that integrates with ERPs, billing systems, or e-commerce platforms to deliver accurate tax determination on every sales and purchase transaction. The solution maintains the latest rules and rates for sales & use tax, value added tax, as well as industry-specific tax content for retail, leasing, and communications taxes. Vertex O Series is available as an on-premise or on-demand (hosted) deployment.