[ploxiln]

https://opentaxsolver.sourceforge.net/

It's just a bit too much grunt work to make something that lots of people really want to use. Tax codes change very year, there are 50 states in the US with different tax codes, it's a lot of work to review contributions (are you a tax lawyer familiar with all 50 states ...)

Lots of successful open source projects are started by one person, who spends a few years making something very useful for themselves, and sharing it, then slowly growing the contributor pool. But this kind of project is a lot more work than just doing your own taxes! And nobody wants to use it as-is 2 years later, it needs more maintenance work every year to be baseline useful, a lot more than it takes to just do your own taxes.

[noisy_boy]

Moreover, experts like tax lawyers don't have any incentive to contribute; if the system turns out to be that simple and effective, they don't have much left to do.

[amelius]

Perhaps LLMs would be a perfect fit for working through tax code and generating a large set of computer-readable business rules from it.