Prospective vs. Retrospective ACO Attribution: Why It Changes How You Manage Patients

Here's a question that trips up a lot of ACOs: if your shared savings and losses depend on which patients get counted in your final panel, when do you actually find out who's on that panel? For a quarter of Medicare Shared Savings Program ACOs, the answer is before the year even starts. For the other three quarters, the answer is after the year is already over. Same program, two completely different answers, and the one your ACO picked changes how you should be managing patients all year long. In this video, I break down how CMS actually builds an ACO's patient panel, and what changes depending on which assignment method your organization elected. We cover: The two-step plurality test CMS runs for every beneficiary: primary care providers first, specialists only as a fallback. Prospective assignment, where your panel is locked in before the year starts and stays fixed all year. Preliminary prospective assignment with retrospective reconciliation, where your list is only a quarterly estimate until CMS reruns the test after the year closes. Current 2026 adoption numbers straight from CMS: 25% of ACOs use prospective assignment, 75% use retrospective reconciliation. What actually happens when two providers are tied for the same patient (it is not a coin flip). And how each method should change what your care management team prioritizes day to day. Sources: 42 CFR Section 425.402, Basic assignment methodology (eCFR, current) CMS, Medicare Shared Savings Program: Shared Savings and Losses and Assignment Methodology Specifications (official technical methodology specification) CMS, 2026 Shared Savings Program Fast Facts Pelica, The Medicare Shared Savings Program (MSSP), Explained (industry commentary, used for framing only) About the creator: Toni M. Appelberg-Parks, MBA-HM/LM, CVBA, CDEO, CDEI, CRCR, CPC, CSBI, CPPM, CPCO(c) is President and Principal Consultant of Help4Docs, helping providers, coders, and CDI teams document and code so it holds up under audit. Learn more at help4docs.com. #RiskAdjustment #HCCCoding #MSSP #MedicareSharedSavingsProgram #ACOAttribution #ValueBasedCare #ClinicalDocumentationIntegrity #MedicalCoding #HealthcareCompliance #Help4Docs