Social Security overpaid beneficiaries by nearly $17 billion, the report estimated, between October 2003 and February 2014.
The agency was able to recover about $8.1 billion of it, the report said.
Many of the payments were delivered to people who either were no longer disabled or to earned too much money to qualify. Some payments went to people who were in prison or had died.
The inspector general followed a randomly selected sample of 1,532 over that 10-year period who either received disability benefits or supplemental security income for the poor.
Auditors found that 45 percent of the beneficiaries were overpaid at some point during the decade by $2.9 million. Based on that result, the inspector general estimated Social Security overpaid $16.8 million from 2003 to 2014.
The report comes just a year before the Social Security Disability Trust Fund is projected to be exhausted, and lawmakers on Capitol Hill are divided over how to handle the shortfall. If Congress fails to act, beneficiaries would receive a nearly 20 percent cut in benefits.
Republicans largely oppose keeping the disability fund afloat by reallocating revenue from the Social Security retirement fund to the disability fund. The GOP-led House in January approved a rule that would make a reallocation of the payroll tax more difficult.
Instead, GOP lawmakers have said they'd like to focus on program integrity initiatives to weed out fraud and abuse to find savings.
Anyone wonder why some unemployed people 'have stopped looking' for jobs ?