Yes but unlikely because this is an example of the Open Source "black hole" where nothing escapes because developers don't find such specialized business applications very interesting.

This requires constant updating and maintenance because tax laws are always changing.

This kind of thing is the bread and butter of SaaS companies though.

It's also exactly the kind of thing companies _wouldn't_ use open source for because if the code gets the tax law wrong they have nobody to transfer liability to. Once you have a corporate entity backing a subscription service, insurance underwriters can understand what's going on and you can finally manage your risks.