Since I have several customers with online stores in Washington State, I need to update their shopping cart checkout procedure to reflect a new rate collection rule that went into effect on July 1, 2008. The rule stipulates that Washington businesses must now collect and report sales taxes based on the delivery address of the buyer. This replaces the old method of calculating sales tax based on the location of the seller.

There are over 400 taxing jurisdictions each with their own code and rate. There is no practical way of figuring out which district a customer is in because any given city or county may have several different rates depending on the exact location of the buyer. People, like me, that perform work at customer sites have had to use a lookup tool on the state web site to find out which code to use for each customer because we've always been required to report based on where the work is performed. This, of course won't work on-the-fly for a web store checkout. Our Department of Revenue has now made available a method of querying their database thru the use of web code and getting the response back with the proper tax code. One method of getting the response is with XML. This was a new twist for me as I've had very little to do with XML or querying outside servers and capturing the results into variables that I can use. After a few hours of testing and research, I came up with a working module. It took another hour or two to trap some possible data entry errors - I don't mind if the response is an error code but I don't want the program to crash all together. I'm still testing for any other entry problems that I might have missed.

Please try out my test module at http://www.johnrdykstra.com/wsst/wsst_test.asp and let me know if you find any bugs or if you need the code for a project.