“To clarify my earlier comments on EITC, not only can an individual amend a prior year return to claim EITC, but an individual who did not file a prior year return may file a return and claim EITC (subject to refund limitations under section 6511 of the Internal Revenue Code),” Mr. Koskinen said.

He insisted, however, that he doubts many illegal immigrants will take advantage of the loophole because they would have to be able to prove their earnings for those years they never filed returns.

“Filers would have to reconstruct earnings and other records for years when they were not able to work on the books,” he said.

Taxpayers must have Social Security numbers in order to claim the EITC, and illegal immigrants aren’t supposed to have numbers. But Mr. Obama’s new deportation amnesty grants illegal immigrants work permits, which are then used to obtain Social Security numbers.