Representative Thaddeus McCotter, Republican of Michigan, resigned Friday, on the grounds that he was basically sick of the job. If he is remembered at all, it will probably be for his comically unsuccessful run for the Republican presidential nomination this year. (Did you not even notice he was running? Exactly.)

I prefer, however, to remember McCotter for advancing one of the worst tax policy ideas of recent times: an income-tax deduction for pet-care expenses.

McCotter’s proposal, the Humanity and Pets Partnered Through the Years (HAPPY) Act, would have allowed individuals to deduct up to $3,500 a year for spending on food, veterinary care, and other costs of owning a pet. In 2009 McCotter said his proposal was aimed at America’s economic troubles: "Well, we've had reports of people having to turn in pets because of the economic recession.… And when you think about the relationship between people and pets and the humane way that it helps people think, it seemed to me to be a good idea.”

The proposal never went anywhere, probably in part because it would have been extremely expensive: According to the Humane Society, 39 percent of U.S. households have dogs and 33 percent have cats. But the impulse to load up the tax code with goodies for favored constituencies is common among members of Congress, and often successful when the target group is smaller and has a better-organized lobby.

With McCotter gone, America’s pets have lost their fiercest tax policy advocate in Congress. But it remains to be seen if he will be replaced by a representative who understands we need to broaden the federal tax base, not narrow it.

(Josh Barro is lead writer for the Ticker. Follow him on Twitter.)

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