Medicare is not one program — it's a layered system of parts, plans, and supplements that interact in ways that are genuinely confusing if you approach it without a map. Getting this decision right can mean thousands of dollars difference per year in premiums, deductibles, and out-of-pocket costs. Here is the 2026 plain-language guide to how the pieces fit and how to choose.
What changed in 2026
- Medicare Advantage enrollment kept rising. More than half of Medicare beneficiaries are now in Medicare Advantage plans, reflecting competitive premiums and bundled benefits — but also driving more scrutiny of prior authorization practices.
- Part D caps improved. The Inflation Reduction Act's drug price provisions continued phasing in; the annual out-of-pocket cap on Part D costs is now capped at ~$2,000 for 2026.
- Medigap Plan F is grandfathered. Medigap Plan F (the most comprehensive) is only available to those who became eligible before January 1, 2020. Plan G is the closest equivalent for new enrollees.
- Star ratings shifted. CMS star ratings for Medicare Advantage plans updated; plans can change quality year over year, so reassessing annually is worthwhile.
Medicare: the four parts at a glance
| Part |
Covers |
Cost notes |
| Part A |
Hospital stays, skilled nursing, hospice |
Usually premium-free if you worked 10+ years; deductibles apply per benefit period |
| Part B |
Doctor visits, outpatient, preventive care |
Standard premium ~$185/mo in 2026; income-related surcharges (IRMAA) apply above ~$103K income |
| Part C (Medicare Advantage) |
Bundles A + B + often D through private insurer |
Premiums vary ($0–$100+/mo); network and prior-auth restrictions apply |
| Part D |
Prescription drugs |
Separate plan or bundled in Advantage; premiums, deductibles, and formularies vary widely |
The core choice: Original Medicare vs Medicare Advantage
This is the first and most consequential decision.
| Factor |
Original Medicare (A+B) |
Medicare Advantage (Part C) |
| Network |
Any Medicare-accepting provider nationwide |
Usually HMO or PPO network; out-of-network costs higher |
| Monthly premium |
Part B premium (~$185/mo) + Medigap if desired |
Often $0–$50/mo above Part B premium |
| Out-of-pocket max |
No cap without Medigap (unlimited exposure) |
Must have an annual OOP max (often $4,000–$8,000 in-network) |
| Extra benefits |
None |
Often includes dental, vision, hearing, gym |
| Prior authorization |
Rarely needed |
Common for procedures and specialists |
| Best if you |
Travel frequently, have complex/chronic conditions, want flexible provider access |
Are relatively healthy, prefer low premiums, stay local |
Medigap (Medicare Supplement) is a private policy layered on top of Original Medicare to cover cost-sharing gaps. Plan G is the most popular for new enrollees — it covers almost all out-of-pocket costs except the Part B deductible (~$240 in 2026). Medigap premiums range from ~$100–$300+/mo depending on age and location.
Part D drug coverage
If you choose Original Medicare, you add a standalone Part D plan. If you choose Medicare Advantage, drug coverage is usually included.
To pick the right Part D plan:
- List all your current prescriptions (drug name, dose, frequency)
- Use the Medicare Plan Finder at Medicare.gov and enter your drugs
- Compare total annual cost = premium + deductible + copays for your specific drugs
- Check that your preferred pharmacy is in-network
The cheapest premium plan is often not the cheapest overall — a $0-premium plan with a high deductible or non-preferred drug tier can cost more than a $35/mo plan with your drugs on Tier 1.
Enrollment windows
| Window |
Dates |
What it covers |
| Initial Enrollment Period |
7 months around your 65th birthday |
First-time enrollment in A, B, D |
| Annual Open Enrollment |
Oct 15 – Dec 7 |
Switch between Advantage and Original; change Part D plans |
| Medicare Advantage OEP |
Jan 1 – Mar 31 |
Switch from Advantage to Original (or different Advantage plan) once |
| Special Enrollment Period |
Triggered by life events (job loss, moving) |
Varies by situation |
Missing the initial enrollment window without employer coverage can trigger late enrollment penalties — 10% of Part B premium per year late, for life.
How to pick
- List your doctors and prescriptions. Neither Medicare Advantage nor Part D helps you if your doctors are out-of-network or your drugs are off-formulary.
- Estimate total annual cost, not just premium. Add deductibles + expected copays + Medigap premium if applicable.
- Assess your travel and health complexity. Frequent travelers or complex chronic conditions usually benefit from Original Medicare + Medigap.
- Check star ratings. Stick to 4-star or above Medicare Advantage plans at Medicare.gov.
- Use a SHIP counselor. State Health Insurance Assistance Program counselors are free, unbiased, and available in every state — they help you compare plans without a sales pitch.
Common mistakes
Choosing only by premium. A $0 premium Medicare Advantage plan with a $7,500 out-of-pocket max is expensive if you use significant care. Total cost is the metric.
Not checking your drugs. Formularies change annually. Even if your drug was covered last year, verify it for the new plan year.
Skipping Medigap enrollment at 65. During your Initial Open Enrollment for Medigap (6 months after Part B starts), insurers cannot deny you or charge more for pre-existing conditions. After that window, medical underwriting applies in most states.
Assuming Medicare Advantage covers everything. Prior authorization, network restrictions, and referral requirements can delay or deny care. Read the plan's Evidence of Coverage before enrolling.
What to skip
- Medicare supplement plans that exceed your realistic OOP exposure — if you're healthy and young-65, Plan N (lower premium, some copays) may beat Plan G on total cost for years.
- Medicare Advantage plans below 3 stars — lower-rated plans have more complaints and worse outcomes data.
- Annual plan-switching without running the numbers — plan hopping is disruptive and switching back to Original Medicare + Medigap after being in Advantage may require medical underwriting.
FAQ
When should I enroll in Medicare if I have employer coverage?
If your employer has 20+ employees, you can delay Medicare without penalty while covered. Under 20 employees, Medicare becomes primary — enroll at 65 to avoid gaps.
Can I have both Medicare Advantage and Medigap?
No. Medigap only works with Original Medicare (Parts A and B). If you enroll in Medicare Advantage, you cannot use a Medigap policy.
What is IRMAA?
IRMAA (Income-Related Monthly Adjustment Amount) is a surcharge on Part B and Part D premiums for higher earners. It kicks in above roughly $103,000 for single filers and scales up significantly. It's based on income from two years prior.
Is there a penalty for not enrolling in Part D?
Yes — 1% of the national base beneficiary premium per month you go without creditable drug coverage, assessed for as long as you have Medicare. Enroll even if you currently take no medications.
Where to go next
See How to appeal a medical bill in 2026 for managing costs after care is received, What is a deductible in 2026 to understand how deductibles work across plan types, and Best HSA providers in 2026 if you are transitioning from an HSA-eligible plan before Medicare enrollment.