I was about to write a post on Paul Krugman’s excellent recent post on taxes, but commenter Matthew Lesich on Steven Landsburg’s blog beat me to it. Still, comments often get lost and so I’ll make the point anyway.

In criticizing Mitt Romney’s claim that 47% of Americans don’t pay income taxes, Krugman points out that although this may be true in a particular year, it’s not true over the life cycle. Krugman writes:

This work [of the Hamilton Project] makes a crucial point: even aside from the fact that there are other taxes besides the income tax, even aside from the larger point that lower-income working Americans are hardly grifters, the fact is that the vast majority of Americans do pay income taxes at some point in their life:

He then presents a striking table showing that the age at which the highest percent of Americans pay income taxes (almost 80% of them) is the early 50s.

This makes sense. Think about students who work at jobs over the summer. Even those who make good money for 3 months pay little or no income taxes. Or think of people who retire and get Social Security and whose other income is, say, $10,000, typically not enough to put them in a federal income tax bracket above zero. They may own their homes outright and may have $100,000 or more sitting in a low-interest bank account. They don’t pay federal income taxes either.

But here’s the interesting thing that explains the snarky tone of my title for this post: This same life-cycle reasoning applies to income. After all, it’s income that results in income taxes. Yet, even though I have probably read at least 70% of Krugman’s popular writing over the last 12 years–and probably over 80% of what he has written on income and taxes–I can’t recall his ever discussing the life cycle of income. I think he talks about high-income people as “the rich,” thus not making the distinction between income and wealth. If he had talked about income over the life cycle, he would have noted that the data at a point in time show more inequality than exists over the life cycle.

So here’s my challenge: prove me wrong. Provide a link to something in the popular literature in the last 12 years–NY Times, etc.–that has Krugman pointing out that there’s a life cycle to income. It has to be in the context of the discussion of the controversial topic of income inequality and not just in the narrower context of technical economics, consumption functions, etc. If someone provides me a certifiable quote, then I will do something that probably some of you would love to see me do: write another post in which I apologize to Krugman. And not just the mealy-mouthed politician’s non-apology apology–“If I have done wrong, then I apologize”–but a real apology.

Game on.