Our Townhall cousin Conn Carroll was way ahead of the game on this, warning back in December that handing out Social Security numbers to illegals under Obama’s new executive amnesty was a momentous development. Illegals are already eligible for some tax credits, he noted at the time, but the real money is in the Earned Income Tax Credit, which can add up to thousands of dollars for low earners with multiple children. Illegals can’t get the EITC, though, because the law requires a Social Security number to apply and they don’t have Social Security numbers. Until now.

So they’ll be able to claim the EITC going forward, which means untold billions in wealth transfers from American citizens to our new quasi-legal class of self-invited “guest workers.” And not just going forward, as it turns out: Under the law, you can claim the EITC retroactively for the three previous years by filing amended returns for those years. Surely that doesn’t apply to illegals too, wondered GOP Rep. Mick Mulvaney at yesterday’s House hearing on the IRS. After all, their status during the last three years was fully illegal, sans Social Security numbers. Surely they can’t claim benefits retroactively for those years now.

They sure can, says IRS chief John Koskinen:

“Under the new program, if you get a Social Security number and you work, you’ll be eligible to apply for the Earned Income Tax Credit,” Mr. Koskinen said.

He said that would apply even “if you did not file” taxes, as long as the illegal immigrant could demonstrate having worked off-the-books during those years.

That expands the universe of people eligible for the tax credit by millions. He said only about 700,000 illegal immigrants currently work and pay taxes using an Individual Taxpayer Identification Number, but as many as 4 million illegal immigrants could get a stay of deportation and work permits under the temporary amnesty, which would mean they would be eligible to claim back-refunds if they worked those years.

Not all illegals will file back-dated returns — some may have earned enough income that they’ll end up owing the feds even with the EITC taken into account — but plenty will. And the fraud potential is limitless. Ben Sasse and Ron Johnson, denouncing this scheme as a way of paying “amnesty bonuses,” wonder if illegals will be able to claim dependent children for EITC purposes if those children still reside in the illegal’s country of origin. If the point of the EITC is to give lower- and middle-class taxpayers a little extra change to help support their kids, what should it matter to our amnesty-friendly administration if those kids live in Mexico City or Dublin or Beijing? They still need supporting. You trust illegals to be honest about just how large their families are in reporting their dependents for EITC calculations, don’t you?

The best part here is when Mulvaney asks Koskinen what the White House thinks of all this and Koskinen says he doesn’t know because … they haven’t discussed it with him. That’s a gross dereliction of duty but oddly apropos for the way Obama’s team has handled this amnesty all along. It was never about diligently fixing a policy problem; it was about fixing a political problem, a gift to the lefty base and to Latino voters whom Democrats are hoping to hold onto in 2016. Why should Obama care about the fiscal nuts and bolts of a new program that’s designed, transparently, as a mega-pander to favored groups?