Last week’s Health Management Associates (HMA) Weekly Roundup reviewed the Calendar Year (CY) 2027 Payment Policies Under the Physician Fee Schedule and Other Changes to Part B Payment and Coverage Policies; Medicare Shared Savings Program Requirements; and Medicare Prescription Drug Inflation Rebate Program (PFS) proposed rule (CMS-1848-P). That overview highlighted provisions that signal a broader shift in how the Centers for Medicare & Medicaid Services (CMS) is approaching physician payment, primary care, digital healthcare, and value-based care.
This week, our focus turns to the rule’s proposed changes to the Medicare Shared Savings Program (MSSP).
Why CMS Is Proposing MSSP Changes
The proposed updates are designed to address feedback and challenges that accountable care organizations (ACOs) have identified over multiple agreement periods, including benchmark volatility, concerns about rebasing, and questions about whether financial incentives adequately reward ongoing performance.
CMS is seeking to make the program more predictable while continuing to encourage accountability for quality and total cost of care. The proposals also reflect broader agency goals to make the MSSP more attractive to current and prospective ACOs, strengthen primary care, and improve access for beneficiaries in underserved and provider shortage areas. The impact, however, will vary by region and practice.
In a July 27, 2026, paper, CY 2027 MSSP Proposed Rule Analysis: What the Medicare Shared Savings Program Changes Mean for ACOs, Wakely, an HMA Company, explains that the financial effect of certain provisions depends on an ACO’s track, agreement period, historical savings, regional efficiency, risk profile, beneficiary assignment, and provider growth strategy.
Key Proposed Changes to MSSP
Several proposed changes stand out for ACO leaders and provider organizations, including:
- Higher Shared Savings for BASIC Level E ACOs. CMS proposes to increase the BASIC Level E shared savings rate from 50 percent to 60 percent for agreement periods beginning in 2027 or later. This change could make the highest-risk BASIC track more attractive relative to other options and improve financial returns for ACOs that are successfully managing cost and quality performance.
- Changes to Benchmark Methodology. CMS proposes to modify how prior savings are incorporated into future benchmarks. The changes are intended to better recognize organizations that have generated savings while addressing long-standing concerns among providers that benchmark rebasing can diminish incentives for high-performing ACOs over time.
- New Accountable Care Prospective Trend (ACPT) Guardrails. The proposal would establish guardrails and annual recalculation mechanisms for the ACPT to reduce the likelihood that prospective spending projections diverge significantly from actual national cost trends. CMS also proposes applying certain guardrail provisions to payment years 2025 and 2026, potentially before many 2027 provisions take effect. For agreement periods beginning in 2027 or later, CMS proposes a two-sided guardrail and annual recalculation approach designed to reduce the risk that the prospective trend materially diverges from observed national spending trends.
- Qualifying Provider Network Growth Incentive and Quality Reporting Updates. CMS proposes a new incentive to support ACO growth and participation. Provider entities should evaluate how beneficiary assignment interacts with provider expansion. As Wakely’s actuaries note, adding providers does not necessarily translate into meaningful assignment growth or financial benefit. The proposed rule also includes changes to quality reporting policies intended to reduce administrative burden and better align program operations with care delivery realities, particularly in rural and underserved areas and markets with access constraints.
Potential Market-Shifting Effects
The proposed MSSP changes could influence market behavior beyond annual participation decisions. By making changes to BASIC Level E economics, refining benchmark rules, and adding protections against certain trend-related volatility, CMS may encourage more organizations to consider where they want to be on the spectrum of risk -based arrangements.
Regionally efficient ENHANCED ACOs that rebase or enter the program in 2027 could face less favorable benchmark adjustments. Lower-risk ACOs may have less room under the proposed risk-adjusted benchmark cap. Organizations that pursue provider growth without corresponding increases in assigned beneficiaries may not realize the intended network growth incentive. These dynamics could create winners and losers based on local market position, historical performance, patient mix, and each organization’s financial and operational strategy.
How HMA and Wakely Can Help
ACO and provider leaders should use the proposed rule period to assess how the MSSP changes could affect their 2027 strategy and near-term financial projections. Current ACOs should revisit payment year 2025 and 2026 forecasts, evaluate the proposed ACPT guardrail, and model how the 2027 benchmark changes may affect renewal, track selection, and downside risk exposure. Organizations considering MSSP entry should evaluate whether the proposed changes improve the business case for participation and what capabilities would be needed to succeed.
Although the proposals focus on MSSP, their significance extends beyond Medicare ACOs. The changes reflect CMS’s broader effort to strengthen participation incentives, improve benchmark stability, and refine value-based payment models based on operational experience. As a result, the proposals may influence how Medicare Advantage plans, Medicaid programs, and commercial payers structure risk arrangements.
Providers and partners should also prepare comments grounded in data and operational experience. HMA and Wakely help ACOs, providers, health systems, payers, enablement organizations, and investors evaluate the policy, actuarial, operational, and market implications of Medicare accountable care changes. Our teams support MSSP strategy, benchmark and shared savings modeling, risk assessment, provider network analysis, care management design, comment letter development, and implementation planning.
As CMS considers comments and moves toward a final rule, organizations should not wait to understand how the proposed MSSP changes could affect participation decisions, market strategy, and accountable care capabilities. HMA and Wakely can help stakeholders translate the proposed rule into actionable scenarios and prepare for the financial and operational choices ahead.