A common tax rate on all forms of capital income

I always look forward to Willem Buiter's posts, and his latest, on a common tax rate on all forms of capital income is absolutely spot on. In fact I've added it to my manifesto.

I especially like the added justification on the end:

[stop the] privately profitable but socially unproductive labour from tens of
thousands of tax lawyers, tax accountants and other tax efficiency experts and
free them for socially productive labour