[ethbro]

This seems kind of like the "What is / isn't gerrymandering?" problem.

I am not an accountant, but couldn't most corporate structures be reimagined by taxing authorities as an idealized "single company"?

Then calculate the difference between taxes that would be owed by that company vs the actual structure?

If there's a statistically significant discrepancy, require the company to provide a rationale. Or pay some penalty.