Medicare education
Medicare Supplement plans
A Medicare Supplement, also called Medigap, helps pay the costs Original Medicare leaves to you. The decisions that matter are which plan level, which company, and most of all, when you enroll.
How it works
Original Medicare pays its share of your medical bills, and a Supplement helps pay some or most of what's left, depending on the plan level you choose. You keep Original Medicare as your primary coverage, which means you can see any provider in the country that accepts Medicare, with no networks and no referrals.
A Supplement doesn't include prescription drug coverage, so most people pair it with a separate Part D plan. That's worth doing even if you don't take any medications now: going 63 days or more without drug coverage after your initial enrollment window can add a permanent late enrollment penalty to your premium later.
The monthly premium is typically higher than a Medicare Advantage plan. In exchange, there's no prior authorization required for care, and your costs are more predictable once you're using it. For many people, that's what makes the higher premium worth it.
Timing is the part people miss
When you first enroll in Part B at 65, you get a six-month Medigap Open Enrollment Period. During that window, companies must accept you regardless of your health history, what's called a guaranteed issue right, meaning you skip medical underwriting entirely. After it closes, medical underwriting can apply in many situations, meaning a company can review your health history and factor pre-existing conditions into your price or whether they'll accept you at all. If underwriting means a Supplement isn't available to you, pairing Medicare Advantage with a Hospital Indemnity plan is one alternative way to manage your out-of-pocket costs.
This is the single biggest reason to understand your choices before you turn 65 rather than after. Our Turning 65 Resource Center lays out the full timeline.
The plan letters, explained
Medigap plans are standardized into a handful of letters, and the letter is what determines the benefits, not the company selling it. A few come up most often:
- Plan G is the most commonly chosen option for people newly eligible for Medicare. It covers everything Original Medicare leaves behind except the Part B deductible.
- Plan N costs less than Plan G in exchange for small copays on some office visits and emergency room trips.
- Plan A is the baseline, covering Medicare's core cost-sharing gaps without the extras Plan G or N add.
- Plans K and L share costs with you up to a yearly limit, then cover the rest of the year in full, trading a lower premium for some cost-sharing along the way.
- Plans C and F covered the Part B deductible too, but closed to anyone newly eligible for Medicare on or after January 1, 2020. If you already have one, you can keep it.
Plans B, D, and M fill in the space between these, each with its own mix of what's covered. Since every company's Plan G matches every other company's Plan G, the letter narrows the real decision down to price and the company itself, which is the comparison we walk through with you.
One more thing worth knowing when weighing G against N: when someone qualifies for a guaranteed issue right, often later in life or after a health change, Plan G is generally the plan they're placed on, not a menu of options to choose from. Over time, that channels an older, sometimes less healthy group of people specifically into Plan G, and its premiums have tended to climb faster as a result. Plan N draws a broader, more self-selected mix of people since it isn't where guaranteed issue enrollees land, which tends to keep its premium increases more moderate. This isn't true for every company every year, but it's part of what we weigh when helping someone choose between the two.
Common questions
Can I use any doctor with a Medicare Supplement?
Yes. Medicare Supplement plans work alongside Original Medicare, so you can see any doctor or hospital in the country that accepts Medicare. There are no networks and no referrals.
When is the best time to buy a Medicare Supplement?
Your Medigap Open Enrollment Period starts when you're 65 and enrolled in Part B, and it lasts six months. During that window, companies can't turn you down or charge you more because of your health history. Outside that window, your health can affect approval and pricing in many cases, which is why timing matters so much.
Why are Medicare Supplement plans named with letters?
The federal government standardized them. A Plan G from one company has the same core benefits as a Plan G from another, which means you're mostly comparing price, the company's rate history, and service. That standardization makes this one of the more comparable products in insurance.
Does a Medicare Supplement cover prescriptions?
No. Supplements help with Original Medicare's out-of-pocket costs like deductibles and coinsurance. Prescriptions are covered separately, through the Part D plan described above.
Can I still buy Plan F or Plan C?
Only if you became eligible for Medicare before January 1, 2020, or you already have one of these plans. Everyone newly eligible after that date chooses among the other standardized plans, most commonly Plan G.
What gives me a guaranteed issue right to buy a Medicare Supplement outside my initial window?
Guaranteed issue means a company has to accept you and can't charge you more based on your health, skipping medical underwriting entirely. A few situations trigger that right outside your initial window: your Medicare Advantage plan leaves Medicare or exits your area, you move out of your plan's service area, you lose employer or union coverage that was paying after Medicare, or your Medigap company becomes insolvent or misled you. There's also a trial right if you joined a Medicare Advantage plan, or dropped a Medigap policy for one, when you first became eligible for Medicare, and you decide within your first year that you want to switch back. Depending on the situation and when you became eligible for Medicare, you're guaranteed access to either Plan F or Plan G, which is why we always check the date alongside the situation.
Comparing Supplement options?
Because these plans are standardized, an independent agency can compare companies side by side. We'll show you how the pricing works and let you decide.