Nicole Maestas, an economist at the Rand Corporation, has examined Social Security data with fellow economist Kathleen J. Mullen, and concluded that in the absence of benefits, about 18 percent of recipients could work and earn at least $12,000 a year, the threshold at which benefits are suspended.
Other economists say that even among those denied benefits, a majority fail to go back to work, in part because of medical problems and a lack of marketable skills.
"In an atmosphere in which there is a concern about fiscal problems, it's always easy to point the finger at groups and say, 'These people should be working,' " said Prof. John Bound, an economist at the University of Michigan, "exaggerating the degree to which the disability insurance program is broken."
Even if claimants have more ambiguous medical cases, once they are granted disability benefits, they generally continue to collect. Of the 567,395 medical reviews conducted on beneficiaries in 2009, Social Security expects less than 1 percent to leave because of improved health.