You probably wouldn't want their fraud detection/audit selection software published. No matter how good it is releasing it gives people a chance to better avoid detection.
I'm mostly thinking of it from a law-abiding citizen perspective. Maybe make some basic tests available to more easily show that I'm not making the stupid mistakes (an extra "0" somewhere or missing a digit somewhere else).
Also, anything that would more easily interface with the IRS's online submission system would be great.
That kind of depends. The software could easily be published without publishing the rules/models that are being run. While knowing what sort of parameters are available to the rules/models might make it easier to identify attacks that aren't going to be found, that's not a given.
You probably wouldn't want their fraud detection/audit selection software published. No matter how good it is releasing it gives people a chance to better avoid detection.