This isn't a new idea, the major complication is that the definition of "family" is much more fluid and fuzzy, both in practice and legally, than a corporation.

This isn't a new idea, the major complication is that the definition of "family" is much more fluid and fuzzy, both in practice and legally, than a corporation. When you create a corporation, there are bright lines as to what is inside the box and what is outside, plus a large number of rules as to how corporate structures can be composed and decomposed in virtually all cases. That said, the tax code for people makes assumptions based on the world that existed in 1970 and is heavily optimized for that. It is a poor fit and creates onerous burdens for the increasing percentage of the population whose lives look nothing like those assumptions. I'd start reform by revisiting the assumptions about peoples' working lives baked into the tax code.