For most of your working life, health insurance is private -- either through an employer or the ACA marketplace. At 65, Medicare enters the picture as a federal health insurance program, and for many retirees it becomes their primary coverage. Understanding how these systems compare -- and how to coordinate them -- is essential planning for anyone approaching retirement.
The decision is not simply "Medicare vs. private." It involves choosing between Original Medicare and Medicare Advantage, deciding whether to add a Medigap supplement, and understanding how Medicare interacts with any remaining private coverage. Getting this wrong can mean paying penalties for life or facing unexpected coverage gaps.
| Part | Coverage | 2026 Cost |
|---|---|---|
| Part A (Hospital) | Inpatient hospital stays, skilled nursing facility, hospice, some home health | Premium-free for most; $1,676 deductible per benefit period |
| Part B (Medical) | Outpatient care, doctor visits, preventive services, durable medical equipment | $174.70/month standard premium; $240 annual deductible; 20% coinsurance |
| Part C (Medicare Advantage) | Replaces Parts A & B through private insurer; usually includes Part D | Varies; many plans have $0 added premium + standard Part B premium |
| Part D (Prescription Drugs) | Prescription drug coverage through private plans | $35--$80+/month; varies by plan and medications |
Important: Original Medicare (Parts A + B) has no out-of-pocket maximum. Without a Medigap supplement, a serious illness could cost you tens of thousands of dollars in cost-sharing. Medicare Advantage plans do have out-of-pocket maximums (capped at $9,350 in-network for 2026).
| Original Medicare (A+B+D) | Medicare Advantage (Part C) | |
|---|---|---|
| Network flexibility | Any provider that accepts Medicare (nationwide) | Network-based (HMO or PPO structure) |
| Out-of-pocket maximum | No limit (Medigap recommended) | Yes -- capped annually |
| Referrals needed | No | Often yes (HMO plans) |
| Extra benefits | None | Often includes dental, vision, hearing, gym |
| Prior authorization | Rarely | Common for procedures and specialists |
| Cost predictability | Low (no OOP max) | Higher (known annual maximum) |
| Medigap eligibility | Yes | No (cannot have both) |
| Best for | Those who want full provider choice, travel frequently, or have complex conditions | Those who prefer lower premiums, extra benefits, and can work within a network |
| Factor | Medicare | Private Insurance (ACA/Employer) |
|---|---|---|
| Eligibility | 65+, or disability/ESRD | Any age; income affects subsidy |
| Part B premium (2026) | $174.70/month base | Varies; $300--$800+/month individual |
| Prescription coverage | Part D (separate) | Included in most plans |
| Dental and vision | Not covered (Medicare Advantage may include) | Varies by plan |
| Provider network | Most providers accept Medicare | Network restrictions common |
| Out-of-pocket max | None (Original); capped (Advantage) | Yes -- required by ACA (max $9,200/individual 2026) |
| International coverage | Rarely | Varies; often limited |
Failing to enroll in Medicare on time results in permanent premium penalties that last for the life of your coverage. The enrollment rules are strict and exceptions are limited.
Note: If you are still working at 65 with employer coverage from a company with 20 or more employees, you can delay Medicare without penalty. Your employer coverage is primary. If your employer has fewer than 20 employees, Medicare becomes primary at 65 -- enroll during your IEP to avoid the late penalty.
If you choose Original Medicare, Medigap (Medicare Supplement) plans -- sold by private insurers -- fill the cost-sharing gaps. There are 10 standardized Medigap plans (labeled A through N). The most popular is Plan G, which covers the Part A deductible, Part B coinsurance, and all other cost-sharing except the Part B deductible ($240 in 2026).
| Medigap Plan | What It Covers | Estimated Monthly Premium |
|---|---|---|
| Plan A | Basic benefits only (Part B coinsurance) | $80--$200/month |
| Plan G | All gaps except Part B deductible -- most popular | $120--$350/month |
| Plan N | Part B coinsurance with some copays -- lower premium option | $90--$250/month |
| Plan K | Partial coverage of most benefits -- 50% cost-sharing | $50--$120/month |
| Plan L | Partial coverage of most benefits -- 75% cost-sharing | $70--$160/month |
A 67-year-old with a chronic condition requiring regular specialist visits and occasional hospital stays is comparing two paths at renewal time. Here's how the annual cost picture typically compares for someone with above-average healthcare usage:
| Original Medicare + Plan G Medigap | Medicare Advantage (typical plan) | |
|---|---|---|
| Part B premium | $2,096/year | $2,096/year |
| Medigap or plan premium | $2,400/year (Plan G average) | $0-$600/year (many $0 premium plans) |
| Part D premium | $600/year (separate) | Usually bundled, $0-$400/year |
| Out-of-pocket for specialist visits and hospital stays | Near $0 (Medigap covers nearly all cost-sharing) | $1,500-$4,000 depending on plan and usage |
| Total annual cost (moderate-to-high usage) | ~$5,100 | ~$3,600-$7,100 |
For this specific profile -- someone with predictable, above-average medical usage -- the Original Medicare plus Medigap combination often produces more predictable total costs, even though the upfront premium looks higher, because nearly all cost-sharing is eliminated. A healthier retiree with minimal medical usage would likely see the comparison favor Medicare Advantage, since they'd be paying a low or $0 premium and rarely hitting meaningful out-of-pocket costs in the first place. The right choice depends heavily on your actual expected usage, not just the headline premium -- which is exactly why this decision deserves a full comparison rather than defaulting to whichever option has the lower advertised cost.
Switching from Medicare Advantage back to Original Medicare is allowed during the Medicare Advantage Open Enrollment Period (January 1 - March 31) or the annual Open Enrollment Period (October 15 - December 7), but there's a catch: if you want to add a Medigap policy at that point, you've likely lost your guaranteed-issue right. Outside of your initial Medigap enrollment window, insurers in most states can medically underwrite you, meaning a Medigap application after developing a health condition could result in denial or a significantly higher premium. This asymmetry -- easy to switch into Medicare Advantage, harder to switch back out with full Medigap protection -- is worth weighing carefully before choosing Medicare Advantage for cost reasons alone if you think your health needs might change.
The 65 transition requires coordinating several decisions simultaneously. Here is a practical timeline:
Higher-income Medicare beneficiaries pay more for Part B and Part D through the Income-Related Monthly Adjustment Amount (IRMAA). This surcharge is based on your income from two years prior (your 2024 tax return affects your 2026 Medicare premium).
| Individual Income | Part B Monthly Premium (2026) | Additional Monthly Cost |
|---|---|---|
| Up to $106,000 | $174.70 | None |
| $106,001--$133,000 | $244.60 | +$69.90 |
| $133,001--$167,000 | $349.40 | +$174.70 |
| $167,001--$200,000 | $454.20 | +$279.50 |
| Above $500,000 | $594.00 | +$419.30 |
If you had a one-time income spike (business sale, Roth conversion, large capital gain) that pushed you into a higher IRMAA tier, you can appeal using SSA Form SSA-44 to report a life-changing event. Retirement itself qualifies as a life-changing event that may reduce your IRMAA surcharge.
Most Americans become eligible for Medicare at age 65. People under 65 can qualify if they have received Social Security Disability Insurance (SSDI) for 24 months, have ALS (Amyotrophic Lateral Sclerosis), or have End-Stage Renal Disease (ESRD).
Yes, with some important caveats. If you are still working and have employer coverage, you can delay Medicare without penalty. If you are not working or your employer has fewer than 20 employees, you should enroll in Medicare Part B during your Initial Enrollment Period to avoid a permanent late enrollment penalty.
Part A (hospital) is premium-free for most people (if you or a spouse paid Medicare taxes for 10+ years). Part B has a monthly premium ($174.70 in 2026 for most beneficiaries). Part D (prescription drug coverage) also has a premium. Medicare Advantage (Part C) premiums vary widely -- some plans have $0 premium.
Medicare Advantage is private insurance that contracts with Medicare to provide your Part A and Part B benefits, usually bundled with Part D drug coverage and often including extras like dental and vision. You pay your Part B premium plus any plan premium. Plans have networks similar to HMOs or PPOs and often have lower out-of-pocket costs than Original Medicare.
Original Medicare has no out-of-pocket maximum -- you can face unlimited costs in a catastrophic illness. Medigap plans fill these gaps by covering Part A and Part B cost-sharing. If you choose Original Medicare (not Medicare Advantage), a Medigap plan is strongly recommended to cap your exposure.
Yes. Medicare can work alongside employer coverage, retiree coverage, or a Medigap supplement. When you have two coverages, one acts as primary (pays first) and one as secondary (picks up remaining costs). Medicare is usually secondary to active employer coverage and primary to retiree coverage.
IRMAA (Income-Related Monthly Adjustment Amount) is an additional premium surcharge for higher-income Medicare beneficiaries. In 2026, individuals earning over $106,000 (or couples over $212,000) pay more than the standard Part B and Part D premiums. The surcharge is based on your income from two years prior.