Summary: Pursuant to a congressional request, GAO reviewed: (1) federal and state agencies' use of the Social Security Administration's (SSA) unrestricted state death information; and (2) the estimated savings of sharing SSA restricted state death information. GAO found that: (1) the largest federal agencies have made progress in obtaining and using SSA death information, but some federal agencies and most state agencies have not requested the information; (2) the Department of the Treasury is working with agencies to resolve problems that make it difficult to assess the results of beneficiary matches with SSA death information; (3) the Coast Guard is the only agency that has met the Treasury's reporting requirements and the Department of Defense is the only agency that has not submitted reports; (4) agencies' use of restricted state death information could result in substantial savings by preventing erroneous payments to deceased beneficiaries; and (5) SSA unrestricted death information is inaccurate to a significant extent.