HMO vs. PPO: The Two Main Network Models
| Plan Type | Network Rules | Out-of-Network Coverage | Referrals Required? |
|---|---|---|---|
| HMO (Health Maintenance Organization) | Must use in-network providers for all non-emergency care | None (emergency only) | Yes — PCP referral usually required for specialists |
| PPO (Preferred Provider Organization) | In-network preferred; out-of-network allowed | Yes, at higher cost-sharing | No referrals required |
| HMO-POS (Point of Service) | In-network primary; out-of-network with referral and higher cost | Limited, with referral | Yes for out-of-network |
| PFFS (Private Fee-for-Service) | Any provider that agrees to the plan’s terms | Varies | Usually no |
The Most Common Network Problems
Your Doctor Leaves the Network
Provider networks are renegotiated annually. A doctor who was in-network January 1 may not be by January 1 of the following year. When this happens mid-treatment — especially for ongoing conditions — continuity of care is disrupted. You must either find a new in-network physician, pay out-of-network rates to continue with your current doctor, or wait until the next enrollment period to change plans.
Specialist Access Is Restricted
HMO plans require a referral from your primary care physician to see a specialist. This adds an extra step for every specialist visit and can create delays. More problematically, the specialist you need may not be in-network at all—particularly for highly specialized fields like certain oncology subspecialties, rare disease specialists, or specific surgical subspecialties.
Major Medical Centers Are Excluded
Institutions like MD Anderson Cancer Center, Cleveland Clinic, Mayo Clinic, Johns Hopkins, and Memorial Sloan Kettering are not in-network for many Medicare Advantage plans. If you receive a serious diagnosis and want access to one of these centers — as many seniors do — your plan may not cover it.
Geographic Restrictions for Travelers
Medicare Advantage plans are tied to a service area — usually a county or group of counties. If you spend winters in Florida and summers in New York, your plan covers emergency care when you’re away from home, but not scheduled appointments. You cannot see your Florida cardiologist under your New York-based Advantage plan unless they’re in-network, which they almost certainly are not.
Hospital-Based Specialists Are Often Out-of-Network
Even at an in-network hospital, not all physicians may participate in your plan’s network. Anesthesiologists, emergency medicine physicians, radiologists, and pathologists are typically employed by the hospital or a separate medical group — and may not be in your plan’s network even when the facility is. This can result in unexpected out-of-network bills for care received at an in-network hospital.
How to Verify Networks Before Enrolling
Don’t rely on the plan’s marketing materials or the claims of a sales agent. Verify independently:
- Go to the plan’s website and use the provider search tool to confirm your specific doctors are in-network (by name, not just specialty)
- Call your doctors’ billing offices directly and ask: “Do you accept [specific plan name and ID] for Medicare Advantage?”
- Confirm your preferred hospital and any specialty hospitals you might need are in-network
- Check for major cancer centers or specialty hospitals if you have or are at risk for conditions that might require them
- Repeat this verification every fall during Annual Enrollment, since networks change January 1
What to Do When a Doctor Leaves Your Network
- Request a continuity of care exception. Most plans allow a temporary exception allowing you to continue seeing a recently out-of-network provider at in-network rates while you transition care — typically 30–90 days for ongoing conditions.
- Ask if your doctor has another group affiliation that might be in-network with your plan.
- During Annual Enrollment, switch to a plan that includes your doctor.
- If this is a recurring problem, seriously evaluate whether Original Medicare + Medigap would better serve your need for continuity and freedom of choice.
Can a Medicare Advantage plan force me to change primary care physicians?
If your PCP leaves the plan’s network and you don’t act, you’ll need a new in-network PCP to access covered care under an HMO plan. The plan should notify you when your PCP leaves the network. You have the right to continuity of care for a transitional period — typically 30–90 days — to transfer your care. Contact the plan immediately when you receive notice that your PCP is leaving the network.
What does “network adequacy” mean, and does CMS enforce it?
Network adequacy means a plan must maintain sufficient providers of each specialty type within a reasonable travel distance for enrolled members. CMS has network adequacy standards that plans must meet. However, enforcement has been inconsistent, and rural areas in particular have chronically thin networks. If you believe your plan’s network is inadequate for your healthcare needs, you can file a complaint with CMS through Medicare.gov or 1-800-MEDICARE.
