I-SNPs: Why Enrollment Quadrupled But Most Nursing Homes Still Don't Have One

Between 2006 and 2021, the share of long-stay nursing home residents enrolled in an Institutional Special Needs Plan (I-SNP) quadrupled - from 2.2% to 8.8%, according to a Health Affairs study from Harvard researchers. That sounds like a program hitting its stride. It isn't, at least not evenly: nearly 70% of nursing homes had zero I-SNP residents in 2021, and in more than 60% of U.S. counties, no I-SNP was available. For a program specifically designed to bring better-coordinated, on-site care to the highest-risk Medicare population in the country, that gap between growth and access is the real story. 

What Is an I-SNP?

An Institutional Special Needs Plan (I-SNP) is a type of Medicare Advantage plan that restricts enrollment to people who, for 90 days or longer, have needed or are expected to need the level of care provided in a long-term care facility - a skilled nursing facility (SNF), a nursing facility (NF), an intermediate care facility for individuals with intellectual disabilities, or an inpatient psychiatric facility. A related variant, the Institutional Equivalent SNP (IE-SNP), extends the same model to people living in the community - at home, in assisted living, or in memory care - who can be shown, through an independent state-level assessment, to need that same institutional level of care.

I-SNPs must cover everything Original Medicare covers, plus Part D prescription drug coverage, and typically add benefits built specifically around institutional care: dental, vision, hearing, and enhanced care coordination.

How I-SNPs Work: The On-Site Care Model

What sets an I-SNP apart from other Medicare Advantage plans isn't just who can enroll - it's how care gets delivered. I-SNPs are paid on a capitated basis, meaning the plan receives a fixed monthly payment per enrollee regardless of how much care that person uses. That payment structure gives the plan a direct financial incentive to invest in prevention rather than reaction, which is why most I-SNPs place a dedicated nurse practitioner or physician assistant on-site at the facility, rounding regularly and working alongside the resident's attending physician and the facility's nursing staff.

The goal is straightforward: catch a change in condition - a fever, a fall risk, early signs of infection - before it turns into a 2 a.m. ambulance ride and an avoidable hospital admission. Research on I-SNPs has consistently found this model reduces acute care utilization compared to residents in fee-for-service Medicare or standard Medicare Advantage plans, even as it surfaces separate concerns in other quality domains, like functional status decline. Our own overview of what care management is covers the same underlying principle - proactive, between-visit coordination - that makes this on-site model work.

The Growth-vs-Availability Gap

The data on where I-SNP growth has and hasn't reached is stark:

• Enrollment quadrupled among long-stay nursing home residents, from 2.2% in 2006 to 8.8% in 2021
• Nearly 70% of nursing homes had no residents enrolled in an I-SNP at all, as of 2021
• More than 60% of U.S. counties had zero I-SNP plans available to residents
• Nearly 94% of I-SNP enrollees were dually eligible for both Medicare and Medicaid

That last figure matters for understanding who benefits and who's left out: I-SNPs have become, in practice, heavily concentrated among the dual-eligible population, while most nursing facilities nationwide-and most counties-simply don't have one to offer. Per CMS's page on Institutional Special Needs Plans, a plan can operate a single-facility, county-based service area, which helps explain why availability is so geographically uneven-an I-SNP's footprint is often tied to a specific facility relationship rather than broad regional coverage.

Why I-SNP Access Varies So Much by Facility

Unlike Original Medicare, where every eligible facility bills the same way, I-SNP availability depends entirely on whether a private insurer has chosen to build a plan around a specific nursing home - and insurers make that call based on facility size, payer mix, and the plan's own regional strategy, not on which residents would benefit most. Per Medicare's own guidance on Special Needs Plans, different types of SNPs may be available in different parts of the country in any given year, since insurance companies independently decide where they'll do business. 

The result is a program that can meaningfully reduce hospitalizations where it exists, but leaves large swaths of the country, and the majority of individual facilities, without access to that same model, regardless of clinical need. This uneven access is part of a broader shift toward holding post-acute settings accountable for outcomes beyond discharge, which our CMS TEAM Model guide for hospitals covers in more depth, especially for the hospital-to-SNF handoff.

Common Misconceptions About I-SNPs

• An I-SNP doesn't pay for room and board. It covers medical care the way any Medicare Advantage plan does; the facility's custodial/residential cost is a separate expense, typically covered by Medicaid or private funds. Our guide to Medicare's 2026 consolidated billing exclusions for skilled nursing facilities covers the related billing principle that governs which services a SNF must absorb into its daily rate versus bill separately.
• It's not the same as a standard SNF Part A stay. A Part A skilled nursing stay is short-term and post-hospital; an I-SNP is built around residents for whom the facility is a long-term or permanent residence.
• An IE-SNP requires independent verification. The plan itself cannot own or control the entity that performs the institutional-level-of-care assessment for a community-based enrollee; that must be an impartial third party.
• Changing residence doesn't automatically end enrollment. If an I-SNP enrollee moves, the plan must document that its CMS-approved Model of Care can still be delivered at the new location, or in another contracted long-term care setting.

Where I-SNPs Connect to Circle Health's SNF Programs

Circle Health doesn't operate or sell I-SNPs - that's an insurance product administered by Medicare Advantage plans, not something a care management company runs. But the problem I-SNPs are trying to solve- reducing avoidable hospitalizations through better on-site care coordination - is exactly the problem Circle Health's programs address for the majority of facilities an I-SNP never reaches. With nearly 70% of nursing homes having zero I-SNP enrollees and over 60% of counties lacking an I-SNP entirely, most facilities are on their own to solve the same hospitalization-prevention problem, without a capitated insurer funding on-site clinical staff.

Nearly one in four Medicare patients discharged to a SNF is readmitted within 30 days. For facilities without I-SNP access, the same underlying goal - catching a change in condition before it becomes a hospital transfer is achievable through:

• Care coordination programs in SNFs, using existing staff rather than waiting on an I-SNP relationship
• Remote patient monitoring that gives staff the same early-warning signal an on-site I-SNP clinician would provide
• Chronic Care Management for skilled nursing facilities, pairing with Transitional Care Management for residents with multiple chronic conditions
• Consolidated CMS software for facilities running several of these programs at once for overlapping residents

Conclusion

I-SNPs represent a genuinely different care model for nursing home residents - capitated payment, on-site advanced practice clinicians, and a direct financial incentive to prevent hospitalizations before they happen. The problem isn't the model; it's the map. Quadrupled enrollment growth means little for the nearly 70% of nursing homes and 60% of counties where no I-SNP exists, which is why facility-level care coordination that doesn't depend on a specific insurer showing up remains essential for most long-stay residents.

CMS updates I-SNP availability, enrollment data, and Medicare Advantage rules on a regular cycle, so treat this guide as a starting reference rather than a final word. Always verify current plan availability and coverage rules against the latest CMS and Medicare.gov publications.

Frequently Asked Questions

What does I-SNP stand for?

I-SNP stands for Institutional Special Needs Plan, a type of Medicare Advantage plan restricted to people who need, or are expected to need, 90 or more days of care at a long-term care facility level.

Who is eligible for an I-SNP?

Eligibility requires Medicare Part A and Part B, residence in the plan's service area, and either living in a qualifying long-term care facility or, for an IE-SNP, an independent assessment confirming an equivalent institutional level of care need while living in the community.

Does an I-SNP cover the cost of the nursing home itself?

No. An I-SNP covers medical care the same way any Medicare Advantage plan does. The facility's room-and-board or custodial cost is a separate expense, typically covered by Medicaid or private funds.

Why don't more nursing homes have an I-SNP available?

I-SNP availability depends on whether a private insurer has chosen to establish a plan tied to a specific facility or county. As of 2021, nearly 70% of nursing homes had no I-SNP enrollees, and more than 60% of U.S. counties had no I-SNP available.

What's the difference between an I-SNP and a standard Medicare-covered SNF stay?

A standard SNF stay under Medicare Part A is short-term and follows a qualifying hospital admission. An I-SNP is a long-term Medicare Advantage plan built around residents for whom the facility is a long-term or permanent residence.

How can Circle Health help?

Circle Health doesn't operate or sell I-SNPs, but it runs the on-the-ground Chronic Care Management, Remote Patient Monitoring, and Transitional Care Management programs that reduce hospitalisations for skilled nursing facility residents - regardless of which Medicare plan they're enrolled in, and without requiring the facility to have an I-SNP relationship in place.