Agencies that spend billions of tax dollars on federal benefits struggle to communicate amongst themselves about what happens when a recipient dies, the Government Accountability Office has found.

Once the Social Security Administration learns, for example, of the death of a beneficiary -- based on state records, family members or other agency alerts -- it then has to inform other agencies that pay out benefits. The purpose is to make sure payments are made accurately.

But GAO -- the investigative arm of Congress -- said the way SSA "collects, verifies and maintains" its death records leaves the agency open to a slew of errors.

The agency also fails to verify independently all the parts of the "death reports" before submitting them as final for other agencies to use, GAO said.

SSA also often received submissions of death reports in 2013 with dates more than a year old.

"If these dates of death are accurate, SSA and other agencies may have been at risk of paying benefits to these individuals for long periods after they died," GAO said.

The Office of Management and Budget made almost $108 billion in improper payments for 2012, according to GAO.

GAO also found that in 2012, SSA's inspector general discovered 1.2 million dead Social Security beneficiaries who were not included in the death data -- which can have a direct impact on how other agencies disperse payments.

Furthermore, GAO pointed out SSA lacks "transparency in communicating how it determines agency eligibility and reimbursement costs."