Your tax engine helps your customers charge taxes consistently and accurately across all their transactions. This function is closely related to spend management—and your customers who use Coupa will appreciate having a tight integration between Coupa and your system. You can easily integrate your tax engine with Coupa using REST API.

When you integrate your system with Coupa, your customers will be able to trigger tax callouts to your tax engine automatically when they receive invoices in Coupa. They’ll be able to validate the tax amount by comparing supplier-entered tax on an invoice with the tax calculated by your tax engine. They’ll also be able to take approved invoices in Coupa and record them in your tax engine’s database, allowing for further reporting and analysis.

Coupa supports a native tax callout to a REST webservice that is triggered on submission (for approval) of an invoice. The configured web service will receive Coupa invoice data in a Coupa-defined XML format. The integration layer can transform the Coupa invoice XML data to the appropriate tax engine format and then call the tax engine web service. The Coupa tax callout will also expect the response in a Coupa-defined format. Once the tax engine validates the tax and returns a calculated tax, the integration layer can transform the tax engine response to a Coupa tax callout response format and return the response to Coupa.

Once the invoice is fully approved in Coupa, you can make a subsequent call to the tax engine to record this invoice in the tax engine database. You can do this by calling the Coupa REST API to GET the invoice data, transforming it to the tax engine format, and then calling the tax engine web service.