I would say this is triple taxation. Looking at how "double taxation" is used to refer to taxing at both corporate and individual level of public company profits, this is an additional burden on top of a two level system. Imagine getting taxed on the amount of taxes paid by a company you own shares of. State and federal levels are "double" in the first place.

Triple is a little hyperbolic, as you could probably best describe it with a number between 2 and 3 depending on the tax rate.