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DOTS FastTax (referred to as FastTax or FT) is a publicly available XML and JSON web service that provides sales tax rate information for all US areas based on several different inputs. The service provides zip, city, county, county fips codes, state, tax rates and exemptions. 

FastTax can provide instant sales tax rates for any address, zip code, city or county in the United States.

Developer Guide


This section lists the DOTS FastTax operations and goes into the details behind the inputs and outputs. 


GetBestMatch (Recommend Operation)




GetTaxInfoByZip_V2  (Deprecated) 


Similar to  the Codes, Notes, and Corrections section, this section reflects details on the error outputs that can happen with the service.

Code Snippets and Sample Code

Here you'll find code snippets for various programming languages and frameworks along with links to our sample code page on the web site.

Try The API

This is where you'll go to take the API for a spin.  There you can test our recommended operation GetBestMatch.

Service Reference

In this section you'll find all the different endpoints supported by this service, input and output schema information as well as an opportunity to try the other endpoints as well.

Frequently Asked Questions

This is a list of some of the questions we hear more often that you can reference and get answers on right away.

Integration Basics

Integrating DOTS FastTax into your application should be easy and straightforward. If you are using a common platform, Service Objects may already have sample code built that you can use:

However, if you are using a common platform that does not already have sample code, you can ask Service Objects to build you an example. Email for more details.

Web Service Structure

Web services are methods that integrate with other applications via the web, and encapsulate tricky business logic. Web services are too large of a topic to cover in this document, but Service Objects has developed its web services to be as easy to integrate and as accessible as possible. 
FastTax is a public XML web service that supports SOAP, POST and GET operations. Note that SOAP is done via POST, only with special XML markup in the post-body.

The host path, or physical location of the web service is here:

The location of the WSDL, or Web Service Definition Language document, is here (This is also accessible via the "Service Definition" link.):

NOTE: For rates in Minnesota, please use GetBestMatch.  Minnesota tracks tax rates differently from the rest of the states (they have zip code level rates).  Getting rates based on zip or city and county lookup operations will not necessarily return accurate results.

This WSDL is the definition of the web service, meaning its inputs, outputs, operations, and the like. Most likely, you will have another tool read this WSDL and make the operations available to you in your application. Whenever your utilities or IDE asks for a WSDL path to FastTax, you can provide this one.

Every web service has operations that it offers to subscribers – methods that do different work and return different output. Examining the link above, you will notice several of these operations available, which are described in detail later on.

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