The General Accountability Office has found that errors in Social Security Administration death records have resulted in payments to dead people while benefits are denied to people still living. The GAO, Congress’ investigative arm, announced its findings in a report it made available on Friday.

In one error, the Office of Personnel Management provided $500,000 in retirement benefits to a deceased worker’s son, the report said.

The GAO contends that the inaccuracies led to $108 billion in improper payments in fiscal 2012 to dead beneficiaries. That year, 1.2 million old age and survivors insurance beneficiaries were still active in the agency’s files, even though they were deceased.

The study warns that since the Social Security Administration does not verify death reports from trustworthy sources such as state vital records departments, it risks using erroneous information. This can lead to further problems since the data is relied on by other federal agencies.