Brendan McBride of DBServices shows how FileMaker can integrate with existing web services to provide a more complete solution to your clients. In this instance, the client needs to know all of the proper taxes to collect for a given address anywhere in the country–a daunting task, given that tax code changes are hard to track. McBride uses Avalara, a company dedicated to tracking tax codes by address. Fortunately, Avalara has an API that can be used to grab the info:
In order to find the sales tax for an address in FileMaker, you will need to register with Avalara in order to receive your API key. The API key is what you will pass to Avalara in order for Avalara to recognize you as a user, so treat this key like a password. Once you have the key, you will need to build a URL query to request the sales tax from Avalara using the FileMaker script step Insert from URL. You will also want to make sure that the parameters within your URL are encoded using the FileMaker function GetAsURLEncoded(). Feel free to check out the Avalara Tax Rate API documentation to see how to build the URL.
Better yet, McBride includes a sample download file at the link to help walk you through the process.