On January 28th CMS released the proposed rule updating the benchmarking methodology for renewing ACOs in the Medicare Shared Savings Program (MSSP). In the final rule update to the MSSP in June of 2015, CMS signaled their intent to more thoroughly evaluate the various options for creating a more accurate and equitable financial benchmarking methodology in a future proposed rule, the program revision most frequently requested by stakeholders. The major aspects of this proposed rule include 1) inclusion of regional expenditures as a major factor in establishing an ACO’s benchmark in their second and subsequent performance periods, 2) an additional option for ACOs to transition more quickly to riskbearing tracks and 3) a number of administrative modifications that illustrate growing sophistication within CMS to act as a value-based purchaser. This document provides an overview of these major aspects of this rule, including some implications of the proposed changes. For a detailed summary of the rule, see the Appendix on page three.