TightWind is written by Kyle Baxter. Stay Hungry. Stay Foolish.

Last night, President Obama claimed—again—that Warren Buffett pays a lower tax rate than his secretary. Problem is, that probably isn’t true. Greg Mankiw explained why that is—nearly five years ago:

Another piece of the puzzle is that Mr. Buffett’s tax burden is larger than it first appears, because he is a major shareholder in Berkshire Hathaway.

When the C.B.O. studies the tax burden, it includes all federal taxes, including individual income taxes, payroll taxes and corporate income taxes. In its analysis, payroll taxes are borne by workers, and corporate taxes by the owners of capital. For the richest 1 percent of the population, 9.3 percentage points of their 31.1 percent tax rate comes from the taxes that corporations have paid on their behalf. The corporate tax would undoubtedly loom large if the C.B.O. were to calculate Mr. Buffett’s effective tax rate.