BASE Utilization Files

Healthcare utilization among Medicare beneficiaries is available across multiple data files provided by CMS (these are the SEER-Medicare “BASE” files). Claims data (e.g., inpatient, outpatient bills) are available only for persons enrolled in fee-for-service (FFS) plans. Providers submit these claims to CMS in order to be reimbursed for serviced provided to FFS beneficiaries. Medicare encounter data (i.e., healthcare utilization without cost information) are available for persons enrolled in Medicare Advantage (MA) plans, beginning in 2015. Medicare Advantage Organizations (MAOs) submit encounter data to document diagnoses among their enrolled beneficiaries; the diagnosis information is used by Medicare to determine the MAO’s capitated reimbursement. Hospice and Part D prescription data are available for persons with MA and FFS coverage.

Last Updated: 29 Jan, 2024