ACO (Accountable Care Organization)
A group of doctors, hospitals, and other healthcare providers who voluntarily come together to give coordinated, high-quality care to their Medicare or commercial patients. CMS-recognized ACOs receive a share of savings if they reduce total Medicare spending for their attributed population below a benchmark while meeting quality standards. ACOs can also take on downside risk, where they repay a portion of spending that exceeds the benchmark.
Why this matters for your clinic
ACO participation can add a meaningful revenue stream for clinics with strong care coordination and population health capabilities. Under the Medicare Shared Savings Program (MSSP), the largest ACO program in the U.S., participating ACOs earned $3.1 billion in shared savings/performance payments in 2023, with $2.1 billion in net Medicare savings (CMS MSSP results). For a clinic, the share of that distribution depends on its attributed patient count and performance contribution.
ACOs also change how you think about care delivery. Success is measured on total cost of care for attributed lives, not just encounter volume. That means managing referral patterns, reducing avoidable utilization, and closing care gaps. Clinics joining ACOs without a CFO-level understanding of their per-patient cost structure take on financial risk they cannot quantify.
The ACO REACH model (replacing the Global and Professional Direct Contracting models) allows independent practices to participate in more advanced risk arrangements than MSSP, including full professional risk and global risk tracks. Before entering any of these arrangements, a clinic needs solid per-patient cost data and a financial model that stress-tests the downside.
What good looks like
CMS publishes annual MSSP performance results including total shared savings, participation counts, and quality score distributions. The 2023 MSSP program results showed 480 ACOs participating, with 63% generating shared savings. CMS updates performance data each fall on the CMS website.
Example
A primary care practice joins an MSSP BASIC track (one-sided) ACO with 5,000 attributed Medicare lives. The benchmark total cost of care for their population is $42M per year. In performance year 1, actual spending comes in at $40.5M, generating $1.5M in gross savings. After applying the minimum savings rate of 3.5%, the net savings qualifying for distribution is approximately $1.05M. The ACO retains 50%, distributing roughly $525K across its participating providers. The practice receives a distribution based on its attribution share, net of ACO administrative costs.
From Sorso
We advise clients considering ACO participation to get at minimum 12 months of per-patient cost data before signing a participation agreement. The shared savings upside is real, but so is the operational complexity of managing attributed population cost.
Founder of Sorso. 19 years in corporate finance. Managed a $450M loan portfolio before building a fractional CFO firm exclusively for healthcare clinics.
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