While the White House has said up to 5 million illegal immigrants would be eligible for the two amnesties, the CBO said it expects only about 1.5 million parents and 750,000 Dreamers to take advantage by 2017.

“CBO expects that the parents who are eligible for this program will be less likely than the people who are eligible for the original program to declare their unlawful presence to the government for a three-year deferral; in addition, they may have a harder time proving eligibility,” the analysts said.

Canceling the amnesties would mean those folks don’t come forward and don’t get the work permits that go along with the amnesty, sending many of them back to work off-the-books, which means less tax revenue for the government. The CBO said payroll taxes would take the biggest hit, suffering a $17 billion decline.