There is no single best Medicare plan — the right choice depends on your health, where you live, and how much you want to spend
Medicare offers four main paths: Original Medicare (Parts A and B), Medicare Advantage (Part C), Medigap (supplemental insurance), and Part D (prescription drug coverage). Each one works differently, costs differently, and covers different things. A plan that works well for someone with one chronic condition and three medications may cost far more or cover far less for someone else. The goal is to match the plan structure to your actual medical life, not to chase the cheapest monthly premium.
The best approach is to compare your options every year during Open Enrollment (October 15 to December 7), because plan costs, networks, and covered drugs change annually. Many people stay with the same plan out of habit and miss better options. This guide explains how each plan type works so you can see which structure fits your situation.
Key Takeaways
- Original Medicare covers hospital and doctor visits but leaves you responsible for 20% of doctor costs and has no out-of-pocket limit, so many people add Medigap to cap their costs.
- Medicare Advantage bundles hospital, doctor, and drug coverage into one plan with a monthly premium and an out-of-pocket limit, but requires you to use in-network doctors and often requires prior approval for specialist visits.
- Medigap is supplemental insurance that pays the costs Original Medicare does not cover, but it does not cover prescription drugs — you must add Part D separately.
- The plan that costs least per month is often not the plan that costs least per year once you factor in deductibles, copays, and coinsurance.
- You can switch plans during Open Enrollment each year, and you can switch from Original Medicare to Medicare Advantage or back without penalty if you move or your health changes.
Original Medicare with Medigap: Predictable costs and broad doctor choice
Original Medicare (Parts A and B) is run by the federal government and covers hospital stays, doctor visits, and some preventive care. You pay a monthly premium for Part B (around $165 to $560 depending on income), and Medicare pays 80% of approved doctor costs after you meet a deductible. You pay the other 20%, with no annual cap — if you have a serious illness or need surgery, your costs can reach thousands of dollars in a single year.
Most people on Original Medicare add Medigap, a supplemental insurance policy sold by private insurers. Medigap pays the 20% coinsurance, the deductible, and other gaps in Original Medicare coverage. Plans are labeled A through N, and each letter covers a different set of gaps. Plan G and Plan N are the most common choices today. With Medigap, your costs become predictable: you know your monthly premium, and you know you will not face surprise bills from in-network doctors. You can see any doctor who accepts Medicare, anywhere in the country.
The trade-off is that Medigap premiums can be high — often $100 to $300 per month depending on your age, location, and the plan letter. You also must add Part D (prescription drug coverage) separately. Original Medicare with Medigap works well if you have established doctors you want to keep, if you travel or move frequently, or if you want the simplest possible structure.
Medicare Advantage: Lower premiums, but networks and prior approval
Medicare Advantage (Part C) is an alternative to Original Medicare. A private insurer bundles hospital, doctor, and drug coverage into one plan, usually with a low or zero monthly premium. You pay a deductible (often $0 to $500), then copays for doctor visits and prescriptions. The plan has an out-of-pocket maximum — once you hit it, the plan pays 100% of covered costs for the rest of the year. This cap protects you from catastrophic costs.
The catch is that Medicare Advantage plans use networks. You must use in-network doctors, or you pay much more or nothing is covered at all. Many plans require prior authorization before you see a specialist or have a procedure — the plan must approve it first. If you travel outside your plan's service area, you may not be covered except for emergencies. Plans vary widely by county, so the plan available where you live may be very different from one in another state.
Medicare Advantage works well if you are willing to use a specific network of doctors, if you want a straightforward all-in-one plan, or if you take multiple medications and want drug costs bundled in. It often costs less per month than Original Medicare plus Medigap plus Part D, but only if you stay in-network and do not hit the out-of-pocket maximum.
Comparing costs: What to look at beyond the monthly premium
The monthly premium is only one piece of the cost picture. A plan with a $0 premium can cost far more than one with a $150 premium once you add deductibles, copays, and coinsurance.
| Cost Element | Original Medicare + Medigap | Medicare Advantage |
|---|---|---|
| Monthly premium | Part B ($165–$560) + Medigap ($100–$300) + Part D ($15–$100) | Often $0–$100 |
| Doctor visit copay | Usually $0 with Medigap | $10–$50 |
| Deductible | Usually $0 with Medigap | $0–$500 |
| Out-of-pocket cap | None (unlimited) | $4,500–$7,500 |
| Prescription drug coverage | Part D (separate plan) | Included |
To compare plans fairly, use the Medicare Plan Finder tool at Medicare.gov. Enter your medications, doctors, and pharmacy, and the tool shows you the total estimated cost for each plan for the year. This number — not the monthly premium — is what matters when you are deciding.
When to choose each plan type
Choose Original Medicare with Medigap if: You have doctors you want to keep and they are not all in one network. You travel frequently or move between states. You want the simplest structure and do not mind paying higher monthly premiums for predictable costs. You have complex medical needs and want to avoid prior authorization delays.
Choose Medicare Advantage if: You are comfortable using a specific network of doctors. You want a low monthly premium and do not mind copays at each visit. You take multiple medications and want drug costs bundled in. You rarely travel outside your home area. You want an out-of-pocket maximum to protect against catastrophic costs.
Choose Part D separately if: You are on Original Medicare and need prescription drug coverage. You can pick any Part D plan, even if it is not from the same insurer as your Medigap plan.
How to switch plans or make changes
You can change Medicare plans once per year during Open Enrollment (October 15 to December 7). Changes take effect January 1. If you move to a new state or county, you can switch plans outside Open Enrollment. If you lose employer coverage or become newly may be able to access for Medicaid, you also get a special window to switch.
If you are on Original Medicare and want to switch to Medicare Advantage, you can do so during Open Enrollment without penalty. If you are on Medicare Advantage and want to switch back to Original Medicare, you can also do so during Open Enrollment. Some people switch back and forth depending on their health and costs that year — this is allowed.
To make a change, contact the new plan directly or use Medicare.gov. You do not need to contact your old plan; the new plan handles the switch. Make sure your new plan is active before you cancel the old one, so you do not have a gap in coverage.
Getting help comparing plans
State Health Insurance information Programs (SHIP) offer free, one-on-one counseling to help you compare Medicare plans. A counselor can review your medications, doctors, and costs and help you understand which plan structure makes sense for you. Find your state's SHIP at shiptalk.org or by calling 1-877-839-2675.
Medicare.gov also has a Plan Finder tool where you can enter your medications and doctors and see estimated costs for all plans in your area. The tool is not perfect — it does not always have the most current drug formularies — but it gives you a starting point for comparison.
Your current insurer (if you have one) or your doctor's office may also have resources to help you understand your options. Some employers offer retiree counseling as well.
Frequently Asked Questions
Can I switch from Medicare Advantage back to Original Medicare if I do not like my plan?
Yes, during Open Enrollment (October 15 to December 7) you can switch to Original Medicare without penalty. If you switch, you should also choose a Medigap plan and Part D at the same time, because you will not have coverage for those gaps otherwise. Outside Open Enrollment, you can only switch if you move, lose coverage, or may have access to for a special circumstance.
What happens if my doctor leaves my Medicare Advantage network?
The plan must notify you, and you have the right to switch to a different Medicare Advantage plan or to Original Medicare outside the normal Open Enrollment window. This is called a "may have access to event." Contact your plan when ready to understand your options and any important date.
Do I have to choose a plan every year, or can I keep the same one?
You can keep the same plan if you want to, but costs and coverage change every year. Many people find a better plan by comparing during Open Enrollment. Even if you stay with the same plan, review it annually to make sure it still fits your needs and medications.
What if I cannot afford the monthly premium for any plan?
You may be able to get help paying premiums through the Medicare Savings Programs, which are run by your state. These programs help people with limited income pay Part B and Part D premiums. Contact your state Medicaid office or call 1-800-MEDICARE to learn whether you may have access to.
Can I have both Medicare Advantage and Medigap at the same time?
No. If you are on Medicare Advantage, you cannot also have Medigap. If you switch to Original Medicare, you can then add Medigap. The two structures are separate paths, not combinations.