The agency blames budget constraints.
As a result, seniors seeking information and help from the agency are facing increasingly long waits, in person and on the phone.
The report was done by the bipartisan staff of the Senate Special Committee on Aging. It says Social Security has closed 64 field offices since 2010, the largest number of closures in a five-year period in the agency's history. The agency has also closed 533 temporary mobile offices that often serve remote areas.
The Senate committee is holding a hearing on the report Wednesday afternoon.