The Obama administration has given Social Security numbers to 541,000 illegal immigrants who were granted amnesty under the president's 2012 Deferred Action for Childhood Arrival program, Acting Social Security Administration Commissioner Carolyn Colvin said in a letter released Wednesday.

"By the end of fiscal year 2014, we had issued approximately 541,000 original SSNs to individuals authorized to work under the 2012 Deferred Action for Childhood Arrivals policy since its inception," Colvin wrote to Sens. Jeff Sessions, R-Ala., and Ben Sasse, R-Nev., in response to their March 12 request, reported Breitbart.

That's about 90 percent of the approximately 600,000 illegal immigrants approved for the DACA amnesty program as of December 2014. They now have the opportunity to receive a number of government benefits, from retirement and disability benefits to driver's licenses. Some experts say obtaining a Social Security number could allow illegal immigrants to eventually vote.

Colvin said that the administration doesn't keep track of how many immigrants applied but were denied a Social Security number.

"We have longstanding, rigorous procedures for processing SSN requests. Under out stringent requirements, SSN applicants must present evidence of identity, age, and work-authorized immigration status," Colvin wrote. "As with all SSN applications, we review the evidence submitted for authenticity, and for non citizens, we also verify immigration and work authorization status directly with the Department of Homeland Security (DHS) via an electronic process called the Systemic Alien Verification for Entitlements (SAVE) Program."

Even if illegal immigrants didn't file tax returns or pay taxes, those who received Social Security numbers will be allowed to retroactively claim up to three years of tax refunds under the Earned Income Tax Credit for time they worked illegally, according to the IRS.

Colvin noted, though, that no Social Security numbers had been granted to immigrants who received amnesty under Obama's most recent Nov. 20, 2014 executive action due to an injunction placed against the programs by a federal district court judge.

"We would only issue SSNs to these individuals if DHS began to accept and adjudicate applications and grant work authorizations and documentation evidencing such authorization," Colvin wrote.

Some critics worry that the amnesty programs could result in American taxpayers effectively subsidizing illegal immigrants' federal benefits.

Stephen Miller, a spokesman for Senator Sessions, told The Washington Times, "This grant transfers jobs, wealth and benefits from marginalized U.S. workers directly to illegal workers. One of the most dramatic costs of amnesty - whether legislative or imposed through executive diktat - is the opening of our federal Trust Funds to large numbers of lower-income illegal immigrants."