Medicare Advantage vs Medigap
| Dimension | Medicare Advantage | Original + Medigap |
|---|---|---|
| Extra monthly premium | $0-50 typical | $120-200 (plan G) |
| Out-of-pocket cap | yes - $9,350 in-network (2025) | no cap; Medigap fills ~everything |
| Doctors | HMO/PPO network, referrals | any provider taking Medicare |
| Travel / snowbirds | off-network coverage weakens | works nationwide |
| Prior authorization | common | rare on plan G |
| Extras (dental/vision) | often bundled | none - buy separately |
| Medigap plan | Pays | Watch |
|---|---|---|
| Plan G | everything but the B deductible | the default for new enrollees |
| Plan N | same minus copays ($20 office) | lower premium, small copays |
| Plan F | everything incl. B deductible | closed to post-2020 eligibles |
| High-deductible G | same as G above a big deductible | cheap premium, real exposure |
The fork at 65 is really a personality test with premiums attached. Medicare Advantage bundles your Part A and B into one managed-care plan - an HMO or PPO - usually at a zero or near-zero extra premium, with an out-of-pocket cap and extras like dental and vision bolted on, in exchange for networks, referrals and prior authorizations. Original Medicare plus a Medigap supplement is the opposite trade: full price every month, in exchange for any doctor or hospital that accepts Medicare and paperwork that mostly does not exist.
Bottom line: the $0 premium is the marketing, the cap is the product. A typical Medigap plan G runs 120 to 200 dollars a month on top of the Part B premium everyone pays, against an Advantage plan at 0 to 50 - a gap the calculator prices at 1,000 to 2,000 dollars a year. What the gap buys is a maximum-out-of-pocket that Advantage already includes (9,350 dollars in-network for 2025) versus Medigap's version, which is close to zero unexpected costs at all; and it buys the network you are giving up. Neither is a scam; they are opposite insurance philosophies at opposite prices.
The honest part: the numbers move every year and every county has a different Advantage menu, so the table is the shape of the decision, not a quote. The two traps are procedural: switching from Advantage to Medigap after your first year usually requires medical underwriting, which a new diagnosis can price out of reach - the one-time 12-month trial right exists but only when you first take Advantage. And having both at once is not allowed; Medigap policies do not pay alongside an Advantage plan.
How to use
- Price your local options in the calculator: the typical Advantage premium in your county against a plan G quote - the annual gap is the size of the decision.
- Read the gap as a purchase: it buys the out-of-pocket cap, the extras, and the lower premium on one side; any-doctor access, nationwide coverage and near-zero surprise bills on the other.
- Check your exit before you enter: first-year Advantage has a trial right back to Medigap in most states; after that, switching generally means passing underwriting - so the chronic-condition history in your household belongs in this decision.
Frequently asked questions
Is Medicare Advantage really free?
No - you always pay the Part B premium (185 dollars a month in 2025) plus whatever copays and coinsurance the plan charges when you actually use care. The zero-premium headline describes only the plan's own monthly charge, funded by Medicare paying the private insurer a fixed amount per member. The honest comparison is annual: Advantage's premium savings against its copays, network limits and the 9,350-dollar in-network cap.
What does Medigap plan G not cover?
Exactly one thing: the annual Part B deductible (257 dollars in 2025). Everything else Medicare approves - hospital days, coinsurance, excess charges, foreign travel emergency at 80 percent - plan G pays after Medicare pays its share. That single-gap simplicity is why G is the default recommendation for new enrollees; plan F pays the Part B deductible too but is closed to anyone who became eligible after 2020.
Can I switch from Medicare Advantage to Medigap later?
Not automatically. The guaranteed-issue trial right lets you leave Advantage for a Medigap plan without underwriting only during your first 12 months on Advantage; after that, insurers in most states can decline you or price the policy for pre-existing conditions. There are exceptions - losing employer coverage or a plan closing lets you in without underwriting - but the default planning rule is: pick as if the switch back is expensive, because it often is.
Do I need Medigap if I enroll in Medicare Advantage?
You cannot combine them - federal law bars selling a Medigap policy to anyone enrolled in Advantage, and it would add nothing anyway, since Advantage plans manage their own cost-sharing. The people who should not buy Medigap: anyone planning to stay on Advantage, or anyone eligible for Medicaid or a Part D low-income subsidy that already fills cost gaps. Medigap is a supplement to Original Medicare specifically.
When can I change Medicare plans?
The annual open enrollment window runs October 15 to December 7, when anyone can drop Advantage for Original plus a drug plan or swap Advantage plans; January 1 to March 3 allows one switch between Advantage and Original with one drug plan change. Outside those windows you need a qualifying event - moving out of the plan's service area, losing employer coverage, or a five-star plan opening nearby, which allows a switch any month.
Why does Medigap cost more if Advantage covers the same care?
Because it sells a different product: Medigap has no network to steer you, no prior authorizations to slow you, and its cost-sharing is nearly zero, so the insurer's price is the risk, paid monthly. Advantage keeps the premium low by managing care - networks, referrals, prior auth - and capping the worst case instead of eliminating it. You are not choosing between covered and not covered; you are choosing between a managed gate and an open door with a bigger bill.