Over its entire life, the Internal Revenue Code (like other tax systems) has never tried to tax economic income as such, because of the administrative and liquidity problems that arise from taxing any combination of values consumed and from appreciation (or depreciation) of capital stocks. Instead, the common practice limits tax occasions to a realization of income from sale or other disposition of property. Even then, if the proceeds of the transaction are not cash or marketable securities, as with many corporation reorganizations, taxation is deferred until these assets are converted in cash or marketable securities.

Any effort to eliminate these twin filters by taxing income—and income regardless of realization—will overburden government agencies and private taxpayers, while reducing economic activity. A wealth tax scores even worse by these welfare measures, creating massive problems of evasion and enforcement that will reduce capital formation across the board in the effort to transfer wealth from the ultra-rich to everyone else. A simple tax structure with affordable rates is the only path to economic prosperity.