The Mankiw CV Plan

Greg Mankiw has posted a suggestion for delivering money to people that targets the benefit to those who need it the most.  The idea is clever:

1. Pay people the benefit B.  (This could be spread over many weeks or months.)  Everyone gets the same B.

2. Next year at tax time, compute the ratio r Y(2020)/Y(2019), the ratio of each filer’s 2020 income, net of B, to their 2019 income and capped at 1.  Impose a surcharge of rB on tax liability.  This way people would pay back a proportion of B based on how much they needed it.  If their 2020 income was greater than or equal to 2019, r = 1 and they would repay B in its entirety.  If their 2020 income was zero, r = 0 and there is no surcharge.  (And no tax at all for that matter.)  Partial income losses would lie in between.

Clever and well-intended, but there are problems.

First, what’s income?  Does it include capital gains and losses?  If so, everyone who has a substantial chunk of financial assets will be able to claim zero income in 2020.  What about business losses?  Clearly, if income is defined expansively, as it should be for tax purposes, those who derive income from capital will come out ahead of those who rely on labor.

Second, how will repayment work?  For low to moderate income people who keep their jobs, tax liability for 2020 may be immense—a large proportion of their annual income.  Yes, if such people save all their B they can just apply it to next year’s payment, but how likely is that?  In practical terms, if the country is facing a wave of enforcement actions and bankruptcies a year from now, the repayment mechanism is likely to be abandoned.

Third, what are the incentives?  Mankiw predictably worries about labor supply, but I think the bigger problem is the immense incentive to work off the books.  Instead of saving only your fractional tax rate when you transact in cash, now you will add the savings on your surcharge.  No one who can escape official scrutiny will report any payments or receipts.  If your goal was to drive as much of the economy underground as quickly as possible, you would have succeeded.

I appreciate Mankiw’s attempt to tie provision of government support to the level of need.  One of the virtues of universal, untargeted social insurance, however, is that it requires a smaller enforcement apparatus and doesn’t turn people who play by the rules into suckers.