US Treasury sent $1.4bn of pandemic aid to dead people
The finding was one of several "challenges" uncovered in the official review of federal coronavirus aid.
Since March, Congress has pumped some $2.6tn into the American economy in an effort to shield it from virus slowdown.
But the rush to deliver the money has contributed to errors, inspectors said.
For example, the Government Accountability Office (GAO) report found that the Treasury Department, which was in charge of mailing stimulus cheques to American families, did not check death records, even though some of the tax officials working on the programme said they raised concerns about the risk of erroneous mailings.
The report also warned that the Paycheck Protection Program for small businesses - a low-cost loan fund that accounts for 26% of US pandemic spending - was at "significant risk" of fraud, faulting the Small Business Administration for not cooperating with requests for information about the loans and its plans for oversight.
"Because of the number of loans approved, the speed with which they were processed, and the limited safeguards, there is a significant risk that some fraudulent or inflated applications were approved," the inspectors said.
It said changes to respond to those risks were "essential".
Debate over aid
The report comes as lawmakers in Washington debate whether or not additional aid is necessary.
While Democrats and many economists - including the head of America's central bank - have recommended further relief, pointing to high unemployment, many Republicans have been hesitant to approve more money.
"We should be very, very careful in evaluating what's necessary before we go forward," Republican Senator Pat Toomey said at a recent hearing.
White House officials have said additional stimulus is likely, but that it makes sense to see how the efforts so far are working. Critics say federal programmes have resisted oversight efforts, however.
