What an IPA is
An IPA is a contracting entity. Physicians who own their own practices, and who compete with each other in the same market, join it and let it hold the health plan contract on their behalf. Nothing about the practices changes hands.
The federal definition sits in 42 CFR 417.1, written for the HMO program and still the operative one: an individual practice association is "a partnership, association, corporation, or other legal entity that delivers or arranges for the delivery of health services and which has entered into written services arrangement or arrangements with health professionals, a majority of whom are licensed to practice medicine or osteopathy." Those written arrangements have to set a compensation arrangement established by the entity and, where feasible, provide for sharing records, equipment, and staff.
What the definition leaves out matters as much. Every practice keeps its own tax ID, its own staff, its own EHR, and its own books. A 300-physician IPA looks like one organization to a payer and like 120 separate small businesses to itself. Most of what is hard about running an IPA comes from that gap.
Why IPAs exist
Three pressures created the structure in the HMO era, and all three are still doing work.
Negotiating position. A four-doctor practice has no leverage against a plan that covers most of the county. Two hundred practices signing one contract do.
Infrastructure. Taking delegated risk means running utilization review, credentialing files, claims, quality reporting, and reserves. Almost no independent practice can build that alone. The IPA builds it once and spreads the cost.
Antitrust. Independent practices are competitors, and competitors who agree on price are committing per se illegal price fixing. Joint contracting only becomes lawful when the practices integrate. There are two accepted routes: share substantial financial risk, which is what capitated IPAs do, or clinically integrate, which is what a clinically integrated network does. An IPA that does neither and still negotiates rates is exposed.
How an IPA contracts: capitation and delegation
Two things move from the health plan to the IPA. Money, and work.
Money usually moves as capitation: a fixed per-member-per-month payment for a defined scope of services. Professional capitation covers physician services. Global capitation covers Parts A and B, which puts hospital cost on the IPA's books. Percent-of-premium arrangements exist too. Shared savings on the medical loss ratio and quality bonuses tied to Star Ratings sit on top of whichever base the contract uses.
Work moves as delegation. Under 42 CFR 422.504(i), a Medicare Advantage organization may delegate activities to another party, but the written agreement has to name the delegated activities and reporting responsibilities, provide for revoking them when the delegate performs badly, and require compliance with Medicare rules. The MA organization stays accountable to CMS for all of it. What typically gets delegated:
- Utilization management. Prior authorization and concurrent review against the plan's criteria.
- Credentialing. Primary source verification and a credentialing committee, audited by the plan.
- Claims. Adjudication and payment for capitated professional services.
- Care management. Complex case management, transitions of care, and outreach.
- Quality and risk adjustment work. Gap closure, chart retrieval, and coding accuracy in the practices.
There is a ceiling on how far the risk can be pushed down. 42 CFR 422.208 sets the risk threshold at 25 percent: if a physician or physician group is at more than 25 percent risk for referral services under an incentive plan, that is substantial financial risk, and the MA organization has to arrange stop-loss protection for the group. The regulation names the individual practice association explicitly as the kind of intermediate entity these rules follow through.
IPA vs medical group vs MSO
These three get used interchangeably in conversation and mean different things on paper. The cleanest test between an IPA and a medical group is income pooling, and it comes from the same regulation that defines both.
A medical group's members, per 42 CFR 417.1, engage in the coordinated practice of their profession as their principal professional activity and "pool their income from practice as members of the group and distribute it among themselves according to a prearranged salary or drawing account or other similar plan unrelated to the provision of specific health services." IPA physicians do not pool income. Each practice keeps what it earns.
An MSO is not a contracting entity at all. It sells administration to practices and to IPAs, and it is never a party to the health plan contract.
| IPA | Medical group | MSO | |
|---|---|---|---|
| What it is | A contracting entity for independently owned practices | A single practice organization whose physicians practice together | A services company selling administration |
| Who owns the practices | The individual physicians, separately | The group | Nobody: the MSO owns no clinical entity |
| How physicians are paid | Each practice keeps its own P&L; the IPA distributes capitation surplus and bonuses | Income is pooled and distributed under a prearranged plan | Not applicable; physicians are the customer |
| Party to the health plan contract | Yes | Yes | No |
| Takes medical cost risk | Often, through capitation or shared savings | Often | No, it earns a management fee |
| Main legal constraint | Antitrust and payer delegation rules | Professional licensure and group governance | State corporate practice of medicine and fee-splitting law |
A fourth structure sits alongside these. A CIN is a clinical integration program, often run inside an IPA or a physician-hospital organization, that makes joint commercial contracting lawful without financial risk sharing. An ACO is different again: it is defined by the payer program it joins, not by how the physicians are organized.
Why IPAs matter in Medicare Advantage
Medicare Advantage is the reason most IPAs are still here. Risk scores and Star Ratings are both earned in the exam room, not at the plan. A plan can build a gap list; it cannot make a visit happen. So plans pay IPAs to run the parts of the business that only work at the practice level, and hand them the risk to make sure they do.
That leaves the IPA holding a squeeze. On one side the plan holds it accountable for RAF accuracy, HEDIS rates, readmissions, and total cost of care. On the other side its member practices are still shaped by fee-for-service volume and have no reason to change a schedule for a payer they see 40 patients a month from. The IPA absorbs the difference, which is the actual job. Value-based care only reaches a patient if somebody bridges that gap.
Where IPAs get into trouble
Treating delegation as a transfer of accountability. It is not one. CMS holds the MA organization responsible no matter how many entities sit below it, which is why the delegation agreement gives the plan audit rights and the ability to pull functions back. A failed delegation audit is an operational emergency for the IPA and a compliance line item for the plan.
Negotiating rates without integration. If the IPA is neither sharing substantial financial risk nor running a real clinical integration program, joint rate negotiation is legally exposed. The messenger model, where an agent carries individual practice decisions to the payer without conveying a collective position, exists for exactly that case.
Confusing the roster with the network. IPA membership is usually non-exclusive, so the same physician appears in three IPAs and attribution moves between them. A member list is not a panel, and last year's panel is not this year's.
Taking capitation without reserves. Global capitation without stop-loss coverage and a credible incurred-but-not-reported estimate turns a good year into a solvency problem the following March.
Buying more data. Most IPAs already have every gap list they need. The lists arrive in six plan portals, on six schedules, in six formats, and the practices never see them. The bottleneck is the work, not the data.
How Pelica works inside an IPA
Pelica is live with HealthCare Partners, one of the Northeast's largest IPAs: physician-led, part of Heritage Provider Network, roughly 1,000 providers and 200,000 lives across the five boroughs and Long Island. Its quality, pharmacy, nursing, and risk teams went onto one system and were live in two weeks.
Pelica pulls claims, EHR, pharmacy, lab, and ADT feeds into one member record, then puts an AI copilot on each function. The agents work the queue themselves: they call and text members in the member's language, check plan portals, file their own notes, and hand a member to a person the moment one is needed. Weekly assignment prep for the quality team went from 8 hours to 15 minutes, and adoption across the teams was 100%.
Related terms
An MSO is the administrative company that runs the back office for many IPAs. A CIN is the clinical integration route to lawful joint contracting when the network is not taking financial risk. An ACO is a program-defined entity accountable for the cost and quality of an attributed population. Capitation is how most IPAs get paid, and value-based care is the payment shift that keeps IPAs relevant.
Sources
- eCFR: 42 CFR 417.1, definitions of individual practice association and medical group
- eCFR: 42 CFR 422.208, physician incentive plans and the 25 percent risk threshold
- eCFR: 42 CFR 422.504, Medicare Advantage contract provisions and delegation
- FTC and DOJ: Statements of Antitrust Enforcement Policy in Health Care, August 1996 (Statement 8, physician network joint ventures)
- FTC: Federal Trade Commission Withdraws Health Care Enforcement Policy Statements, July 14, 2023