For ACOs participating in the Medicare Shared Savings Program (MSSP), CMS is implementing rules in 2021 and 2022 for quality reporting which include a sweeping change. This change will require a new reporting approach, in order to aggregate data from electronic health record systems used across an ACO for all patients seen by any provider, regardless of payer or participation in the ACO. In a recent survey, nearly 75% of the ACO respondents indicated concern with the challenge of these requirements. The Web Interface reporting is being sunset, and ACOs need to devote attention to determining their strategy for transitioning quality reporting. Success will require thoughtful planning and experienced system implementation.