Reviewed September 2026.
At Medicare decision time you usually pick a lane: Medicare Advantage (Part C) or Original Medicare + Medigap (Supplement) plus, in most cases, a Part D drug plan. Medigap product basics: What is Medigap. Use the table below to line up network rules, premiums, and worst-year medical costs before you enroll.
Core tradeoffs
| Factor | Medicare Advantage (Part C) | Original Medicare + Medigap |
|---|---|---|
| Provider access | Plan network (HMO/PPO rules); prior auth common | Any provider that accepts Medicare (assignment still matters) |
| Out-of-pocket max | Plan MOOP caps in-network medical cost-sharing: MOOP basics | Medigap fills many A/B gaps; Original Medicare alone has no annual MOOP |
| Premium shape | Often low plan premium + Part B; copays per service | Part B + Medigap premium (+ Part D); fewer per-visit surprises on rich letters |
| Drugs | Usually bundled (MA-PD) | Separate Part D in most cases: Part D donut hole |
| Travel / multi-state | Network and urgent-care rules vary | Broad access wherever Medicare is accepted |
| Extra benefits | Dental/vision/hearing perks common | Medigap rarely covers those extras |
| Switching later | AEP/OEP and trial rights matter; Medigap underwriting can apply after OE | Strongest Medigap shopping in open enrollment: Medigap OE |
Star ratings help compare Advantage contracts, not Medigap letters: Advantage star ratings. Guaranteed-issue Medigap rights are situational: Medigap GI.
Worked sketch: snowbird with specialists
Priya is 66, sees a cardiologist and a rheumatologist in two states, and fills 4 specialty drugs. Priya compares:
| Lane | Monthly money (illustrative) | Care friction |
|---|---|---|
| Advantage PPO with $0 plan premium | Part B ~standard + copays; MOOP $4,500 in-network | Prior auth on infusions; out-of-state specialists may be Tier 2 or non-network |
| Original + Medigap Plan G + Part D | Part B + Plan G ~$140–$200 + Part D ~$40 | Any Medicare provider; drug formulary still needs a Part D check |
Priya lists each doctor’s Medicare acceptance and each drug’s formulary tier before picking a lane. Priya does not assume dental perks offset a denied out-of-network specialist visit.
Decision checklist
- Write every current doctor, hospital, and drug on one page.
- Check Advantage network and prior-auth rules for those names.
- Compare two annual views for Advantage (premiums + expected covered medical cost-sharing, and premiums + MOOP for a high-use year) vs Medigap premium + remaining cost-sharing (for example Plan G’s Part B deductible) + Part D. Do not add covered Advantage copays on top of MOOP; those copays already count toward the max.
- Test snowbird / travel months against network rules.
- Calendar Medigap open enrollment and any state birthday or trial rights before you lock Advantage.
- Re-shop drugs every Annual Enrollment Period even if you keep the same lane.
Educational only. Not Medicare or insurance advice. Premiums, MOOP, and networks change yearly; confirm on Medicare.gov, Plan Finder, and plan documents.