Upon hearing that Greg Mankiw will stop writing transparently illogical op-eds opposing Social Security and favoring upper-class tax cuts if the Bush tax cuts aren’t extended, all I can say is…who thought that the policies I already favor could have such salutary side benefits?
Basically, the effect of letting the Bush cuts expire is so tiny that the only way to make it noticeable is to compound it over 30 years, which reduces his eventual payout from $2,000 to $1,700. (And even that’s probably overstated, since it assumes Mankiw pays all his taxes at their full statutory rate, which virtually no one does.) The rest of the reduction down to $1,000 comes solely from the estate tax. But even on the heroic assumption that you should take this year’s zero rate as the baseline for comparison, the estate tax has an exemption of several million dollars. Unless Mankiw leaves his kids a helluva lot more than they need for a down payment on a house, they won’t pay a dime of estate tax.
This is why the tax posse has such a habit of wildly overstating things. If they don’t, there’s no there there. It turns out that the effect of letting the Bush tax cuts on the rich expire is so minuscule that the only way to make it look sensational is to pick a scenario in which you (a) overstate effective tax rates, (b) compound those tax rates over 30 years, (c) slash the final number nearly in half by ignoring the estate tax exemption, and (d) use this year’s highly unusual zero rate as your baseline. It’s a virtuoso performance.
…see also DeLong.