Cost - It takes very little effort and doesn't cost anything to publish the source code, the project uses a free service called Source Forge. If outside source code contributions are received it will actually result in a net savings because the contributed code is code that participating states didn't have to pay developers to write.

To be a good Neighbor - Many states are implementing Modernized eFile, Streamlined Sales Tax, and other XML-based electronic return systems. Sharing the code with fellow states is a nice thing to do because it helps them accomplish their goals while reducing their costs. Additionally, other agencies and departments could adapt and enhance the code to meet their needs.

Education - People who are studying Java software development could learn by studying our code. Our code has a lot of interesting pieces in it that aren't directly related to taxes (our event logging system, authentication system, unit test setup, etc). Developers of open source software can legally copy and use the code in their projects.

Better Software - With more people using the code and more developers looking at the code, bugs would be more easily spotted and fixed. Sharing the code with the transmitters who send us data allows them to test changes to their software and debug problems more easily. They could examine exactly what our code does with their input and setup their own private testing environment.