Two Roads to Accountability

Medicare is currently running two different theories of how to get value, side by side, on overlapping populations. Understanding how they differ clarifies most of the policy debate around Medicare Advantage.

The two models

	Medicare Advantage	Traditional Medicare ACOs
Who holds risk	A private plan, often passed to provider groups	Provider organizations directly
Payment	Capitation, risk-adjusted, set by bids and benchmarks	Fee-for-service against a spending benchmark
Provider choice	Restricted by network	Open, beneficiaries see any Medicare provider
Utilization management	Prior authorization and network steering	Essentially none
Extra benefits	Funded by rebates	None

What each gets right

MA’s advantage is tools. A plan can build a network, manage utilization, coordinate care, and fund benefits traditional Medicare cannot offer. It has levers, and it uses them.

The ACO’s advantage is alignment without restriction. As the ACO course covered, beneficiaries keep free choice, there is no network to escape, and accountability sits directly with the providers delivering care rather than with an intermediary. The savings are more modest, but they come without the access trade-offs.

Worth remembering: the two models fail differently, which is the honest way to compare them. MA’s characteristic failure is restriction and cost to the program: prior authorization friction, network limits, and payments running above traditional Medicare. The ACO’s characteristic failure is weakness: open networks and limited tools produce real but modest savings, and leakage undercuts them. Neither model is simply better; they trade different things away.

Why both persist

Policy has not chosen between them, and there are reasonable arguments for the mix. MA offers beneficiaries benefits and coordination many value, and it has proven capable of pushing deep risk to providers. Accountable care in traditional Medicare preserves the choice that many beneficiaries prize and avoids paying a private intermediary. CMS has stated ambitions for accountable relationships across the whole program, which in practice means both roads at once.

Key takeaways

• MA delegates accountability to a private plan with networks and utilization management; ACOs hold providers accountable inside open traditional Medicare.
• MA has more tools and offers extra benefits; ACOs preserve free choice and avoid the intermediary.
• They fail differently: MA toward restriction and higher program cost, ACOs toward modest effect, which is why policy has kept both.