What is the "corporate income tax"?

Today's New York Times has an op-ed by Laurence Kotlikoff advocating abolition of the U.S. corporate income tax.  To make this revenue-neutral, he'd accompany it with increasing personal income tax rates.

Kotlikoff claims that "eliminating the United States' corporate income tax produces rapid and dramatic increases in American investment, output, and real wages, making the tax cut self-financing to a significant extent."  Ostensibly the "potential economic and welfare gains are stunningly large," even with an accompanying increase in personal income tax rates.

I looked quickly at the underlying paper by Kotlikoff and several coauthors, which is available here, and had the following concerns:

1) What exactly is the "corporate income tax" that we are repealing in his model?  While this is not entirely clear in the paper, perhaps he means the tax on income from capital that is invested in the U.S.  But this is a very different proposition indeed from the "U.S. corporate income tax."  At present, lots of domestic capital income is earned outside of corporate solution, and not just for tax reasons.. Also, lots of labor income, in an economic sense, can show up as corporate income because owner-employees don't have to pay themselves arm's length salaries.  Kotlikoff may view all this as merely a bunch of second order implementation details, but others might disagree.

More generally, it would be a huge mistake to think of repealing the existing corporate income tax as closely analogous in practice, even just in the steady state without regard to transition issues, to repealing the income tax and replacing it with a well-functioning progressive consumption tax.  The institutional details are just too different and consequential.  But once one recognizes this, one is stuck in the morass of niggling institutional details that make it harder to draw firm conclusions about anything relating to the corporate tax, especially from a very general and abstract model.  See my book, Decoding the U.S. Corporate Income Tax (paperback here, Kindle here), for discussion and explication of the existing corporate income tax system's lack of a coherent economic core.  This of course is not a defense of the existing system, but shows that it's harder than Kotlikoff may realize to determine what repeal of the system actually means.

 2) The paper appears to contemplate consumption and/or wage tax financing to replace the lost corporate income tax revenues.  By contrast, the op-ed speaks of higher personal income tax rates.

3) In the paper, the very large estimates of increased U.S. capital investment and welfare that are cited in the op-ed expressly depend on the lack of matching corporate tax reductions in other countries.  This appears quite unrealistic, especially if the behavioral response is as huge as the paper's results suggest.  The paper deals with the issue of matching corporate tax reductions around the world, which it unsurprisingly finds would significantly reduce the U.S. welfare gain.  Perhaps the op-ed should have acknowledged this point.

4) The paper and model appear to assume that the incidence of the U.S. corporate income tax falls almost entirely on labor, presumably because capital is highly mobile and labor far less so.  To the extent that this bottom line conclusion remains controversial, however, then to some extent the paper has risked assuming its conclusions.  (Not much of a surprise if U.S. workers were to gain from eliminating a tax that is assumed to fall substantially or entirely on them due to the effects of cross-border capital flows.)

Economic models with greater institutional detail than that by Kotlikoff et al do not invariably find this bottom line result to be clear.  (More precisely, some do, but others don't.)  For example, consider this paper, which finds, for state-level corporate income taxes, that  "firm owners bear roughly 40% of the incidence, while workers and land owners bear 35% and 25%, respectively."  States are even more by way of being small open economies than the U.S. as a whole, although admittedly labor mobility might be higher, not just absolutely but also relative to capital mobility, within the U.S. than across national borders.