If your organization is considering forming or joining an Accountable Care Organization, you will want to understand which Medicare beneficiaries the ACO will be held accountable for. After all, the ACO’s performance in the Medicare Shared Savings Program will be judged by the quality, cost, and overall care furnished to these patients. This advisory focuses on the methodology the Centers for Medicare & Medicaid Services proposes to “assign” Medicare beneficiaries to ACOs, as reflected in the recently proposed ACO regulations.

Section 3022 of the Patient Protection and Affordable Care Act (PPACA) requires the Secretary of the Department of Health and Human Services to determine an appropriate method to “assign” Medicare fee for service (FFS) beneficiaries to an ACO based on their use of primary care services. In commentary to the regulations, CMS notes that the term “assignment” in no way implies any limits, restrictions, or diminishment of the rights of Medicare FFS beneficiaries to exercise complete freedom of choice in the physicians and other health care practitioners and suppliers from whom they receive their services.

In fact, CMS indicates it prefers the term “alignment” of beneficiaries, as opposed to “assignment” or “attribution,” because the exercise of free choice by beneficiaries in the physicians and other providers and suppliers from whom they receive their services is a presupposition of the Shared Savings Program.

Under PPACA, CMS can consider beneficiaries’ use of primary care services provided by physicians only when assigning beneficiaries to ACOs, even though other nonphysician practitioners (e.g., physician assistants or nurse practitioners) are included in the definition of “ACO professionals” for purposes of determining whether an entity can participate in the Shared Savings Program.

To correctly associate physicians with a given ACO, CMS clarifies that it will identify an ACO operationally as a collection of Medicare-enrolled TINs (either employer identification numbers (EINs) or Social Security numbers (SSNs)). Each organization applying to be an ACO will be required to provide the TIN for each ACO participant. Primary care physicians (defined as physicians with a designation of internal medicine, geriatric medicine, family practice, and general practice) must be exclusive to one ACO agreement in the Shared Savings Program.