Another 11% were flagged because of missing or incorrect dates of death.
The agency said 251 providers and suppliers had exceptionally high numbers of paid or unpaid claims with service dates after beneficiaries' deaths under Medicare Part B, which includes physician services and durable medical equipment.
Attempts to obtain reimbursement sometimes came many months to more than a year after the patient died. For example, for Part B claims, 63 providers submitted claims for electrocardiogram reports for 30 beneficiaries with an average lag time of 403 days after the beneficiary died, according to the report.
CMS undertook take these actions recommended by federal investigators: