The real problem is not the lack of systems but the ridiculous complexity of tax law. Since the complexity is unlikely to go away any system would have to handle it - and this is not an easy task.

Given that the OP works for an organization which is "focused on digitization of government data" it is quite peculiar that he doesn't understand the problem domain any better. It's quite a joke to think that it's a matter of throwing in some web forms here and there.

In complexity I would say it's up there with his favorite Apollo quote. Maybe not on par - but close. Just thinking about the size of the rule engine which is required makes my head hurt.