Pursuant to a congressional request, GAO reviewed the Social Security Administration's (SSA) efforts to reconcile cases in which employers reported lower employee wages to SSA than to the Internal Revenue Service.

GAO found that: (1) SSA telephoned employers that did not respond to SSA reconciliation letters and that had wage reporting differences of at least $500,000; (2) the telephone success rate was much less than estimated by two SSA studies because the study samples were not reliable or representative and the studies incorrectly attributed the resolution of some cases to telephone reconciliation, rather than to other activities; (3) SSA based its $500,000 threshold on the belief that such a threshold would target cases with the greatest potential for payoff; and (4) other characteristics, such as whether employers had received previous reconciliation letters or filed recent wage reports, could help predict probable success for reconciliation.