From the Government Accountability Office:
Economic impact payments. The Internal Revenue Service (IRS) and the Treasury moved quickly to disburse 160.4 million payments worth $269 billion. The agencies faced difficulties delivering payments to some individuals, and faced additional risks related to making improper payments to ineligible individuals, such as decedents, and fraud. For example, according to the Treasury Inspector General for Tax Administration, as of April 30, almost 1.1 million payments totaling nearly $1.4 billion had gone to decedents. GAO recommends that IRS should consider cost-effective options for notifying ineligible recipients how to return payments. IRS agreed with the recommendation.