Originally Posted by
caseystrom
The best method I have come up with is using geocoding for the latitude and longitude rather than the zip code. According to DOR, the zip code (and plus 4) is not 100% fool proof as new construction sometimes wont get updated in the DOR's database in a timely fashion.
1. Use a geocoding service to convert address to Lat/Lon. Google Maps allows 1000 queries per day and is pretty accurate.
2. Use Lat/Lon against the DOR HTTP response API - dor.wa.gov/Content/FindTaxesAndRates/RetailSalesTax/DestinationBased/LatLongInterface.aspx
Voila. Tax code generated.
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