At 65 you are not choosing between ten things. You are choosing between two routes, and almost every other decision follows from which one you pick.
Route A is Original Medicare (Parts A and B) plus a Medigap policy to pay your share of the bills, plus a standalone Part D drug plan. Route B is a single Medicare Advantage plan from a private insurer that bundles all of it. Every figure below was pulled fresh on September 6, 2026 from CMS, Medicare.gov, KFF and two state insurance department rate charts.
The Two Routes in One Paragraph Each
Route A: Original Medicare + Medigap + Part D. The government pays your claims. You can see any doctor or hospital in the country that accepts Medicare, with no network and no referrals. Original Medicare has no out-of-pocket limit of its own, so the Medigap policy exists to close that hole. Drugs are a separate purchase.
Route B: Medicare Advantage (Part C). A private insurer takes over your Part A and Part B benefits and usually folds in drug coverage, dental, vision, hearing and a gym benefit. Premiums are low or zero. In exchange you use the plan’s network, and the plan decides in advance whether many services are covered.
What Each Route Actually Costs in 2026
The honest comparison is not the monthly premium. It is the total you can be out in a year, premiums plus cost sharing.
| Cost component (2026) | Route A: Original Medicare + Plan G + Part D | Route B: Medicare Advantage |
|---|---|---|
| Part B premium | $202.90/mo ($2,434.80/yr) | $202.90/mo ($2,434.80/yr) |
| Plan premium | Medigap Plan G $177-$498/mo at age 65; Maryland median $247 | $0 for 75% of enrollees; $15/mo average across all enrollees |
| Drug premium | Separate Part D plan, about $36/mo average | Usually included in the plan premium |
| Medical deductible | $283 Part B deductible (Plan G does not cover it) | Varies by plan; many have $0 medical deductible |
| Your share after that | $0 on Medicare-covered Part A and B services | Copays and coinsurance until you hit the plan’s limit |
| Out-of-pocket limit on Part A/B services | Effectively $283 with Plan G | $9,250 in-network maximum allowed; $5,421 average |
| Part D drug out-of-pocket cap | $2,100 | $2,100 |
| Typical healthy year, all in | About $5,800 at the Maryland median | About $2,435 to $2,615 |
| Rough bad year, all in | About $8,200 | About $10,100 at the average limit, up to roughly $14,000 |
Sources: the $202.90 premium, $283 Part B deductible and $1,736 Part A hospital deductible come from the CMS fact sheet published November 14, 2025. Plan G premiums are actual filed rates from the Maryland Insurance Administration’s rate guide as of July 1, 2026 (88 non-tobacco rate rows, median $247 a month at age 65). The Advantage figures come from KFF’s 2026 analysis of the CMS Landscape and Enrollment files. The $2,100 Part D cap and $615 maximum Part D deductible are on Medicare.gov.
Two premium averages disagree slightly and both are worth knowing. KFF’s enrollment-weighted average Advantage supplemental premium for 2026 is $15 a month, while KFF also reports a CMS estimate of $14.00 a month across all Advantage enrollees. Call it $14 to $15. For those who do pay a premium, the average is $59 a month.
The gap in guaranteed spending is roughly $3,400 a year (a median Plan G at $2,964 plus about $432 for Part D). That is the price of the cap. Medigap wins the arithmetic in any year your Advantage cost sharing would have exceeded about $3,400, and loses it in any year you barely use care.
The Out-of-Pocket Maximum Original Medicare Does Not Have
This is the single most important structural difference, and it cuts both ways.
Original Medicare on its own has no annual out-of-pocket limit. Medicare.gov states it plainly: there is no yearly limit on what you pay unless you have supplemental coverage or join an Advantage plan. A long hospitalization means the $1,736 Part A deductible per benefit period, then $434 a day for days 61 through 90, then $868 a day for lifetime reserve days, plus 20% coinsurance on the physician side with no ceiling.
Medicare Advantage is required by federal regulation to cap that. For 2026 the limit may not exceed $9,250 for in-network services and $13,900 for in-network and out-of-network combined, and most plans set theirs lower: the enrollment-weighted average is $5,421 in-network ($4,636 for HMOs, $6,592 for PPOs) per KFF. Those caps apply to Part A and Part B services only. Drugs run on the separate $2,100 Part D cap.
A Medigap Plan G takes a different approach: instead of capping a large number, it pays nearly all of it. Buy Plan G and your remaining exposure on Medicare-covered services is the $283 Part B deductible. Plan N is cheaper and leaves you copays of up to $20 for some office visits and up to $50 for emergency room visits that do not end in admission. See our breakdown of Plan G vs Plan N and the full Medigap cost picture.
Networks and Prior Authorization
The low Advantage premium is financed partly by Medicare’s payments to plans and partly by managing what you use.
Nearly all Advantage enrollees (99%) are in plans that require prior authorization for at least some services, which is rare in Original Medicare. KFF found it is most often required for the expensive things: acute inpatient stays (97% of enrollees), skilled nursing facility stays (95%), Part B drugs (94%) and home health (90%), and rarely for preventive services (6%).
Network size is the other half. KFF reports that Advantage enrollees have access to about half the physicians available to traditional Medicare beneficiaries in their area, on average. More than six in ten individual Advantage enrollees are in HMOs, which generally do not cover out-of-network care at all. Under Original Medicare with Medigap there is no network: any provider accepting Medicare accepts you.
If you have a specific oncologist, a specific academic medical center or a second home in another state, that is not a small detail. It is often the whole decision.
The One-Way Door
You can switch from Medigap into Medicare Advantage during open enrollment (October 15 to December 7) any year you like. Getting back is the part people underestimate.
Federal law guarantees you a Medigap policy in only two windows: your one-time six-month Medigap Open Enrollment Period, which starts the first month you have Part B and are 65 or older, and specific guaranteed issue situations. Outside those, an insurer may medically underwrite you and decline the application or charge more. See the open enrollment period rules for the exact timing.
The two federal trial rights that let you come back:
- You joined an Advantage plan when you were first eligible for Medicare at 65, and within the first year you decide to return to Original Medicare. You can buy any Medigap policy sold in your state.
- You dropped a Medigap policy to try Advantage for the first time, you have been in the plan less than a year, and you want the old policy back. You get your prior policy if the same insurer still sells it, otherwise Plan A, B, C, D, F or G.
Both windows run from 60 days before your coverage ends to no more than 63 days after.
State law can be more generous. Connecticut, Massachusetts and New York require Medigap insurers to issue policies continuously through the year regardless of health, and Maine has a one-month guaranteed issue period each year for Plan A, according to KFF. Washington’s insurance regulator lets anyone already in a Medigap plan B through N switch to another B through N plan at any time with no health screening. Maryland added a birthday rule in 2023: a 30-day window each year, starting on your birthday, to switch to a Medigap policy of equal or lesser benefits without underwriting.
Everywhere else, the practical rule is that the Advantage decision is easy to make and hard to unmake after year one.
Which Route Fits Which Person
Medigap tends to fit people who want predictable costs rather than low costs, who see specialists at institutions that may sit outside a local network, who travel or split the year between states, who have a condition likely to make future underwriting fail, and who can absorb roughly $3,400 a year in extra premium. Nationally, Plan G is the most popular choice, covering 39% of Medigap policyholders.
Medicare Advantage tends to fit people who are healthy right now and want to keep cash flow low, who value dental, vision, hearing and fitness benefits that Medigap never covers, whose doctors are already in a strong local network, and who are comfortable with prior authorization. If money is tight, check Medicare Savings Programs and Extra Help first, because either can beat a premium comparison outright.
Two things to do before signing anything. Price a real Plan G and Plan N quote for your ZIP code rather than a national average, since the same plan letter can differ by hundreds a month between carriers. And if drug costs are the pressure point, look at the Medicare Prescription Payment Plan, which spreads the $2,100 cap across the year.
Bottom Line
Advantage costs less per month and can cost far more per year. Medigap costs more per month and makes the year predictable. For the coverage-and-access side of the comparison without Medigap in the frame, see Medicare Advantage vs Original Medicare. If you are leaning Medigap, start with Plan G pricing, then compare Plan N and, if you were eligible for Medicare before 2020, Plan F. And if a hospital bill lands before any of this is settled, our guide to negotiating medical bills still applies.