Supplemental Medicare insurance: how Medigap fills the gaps

The hospital side has its own exposure. In 2026, the Part A inpatient deductible is $1,736 per benefit period, not per year, so two separate hospitalizations in the same calendar year can each trigger it. Once you pass day 60 of a stay, coinsurance kicks in at $434 per day for days 61 to 90, and $868 per day for the 60 lifetime reserve days you can draw on after that. Skilled nursing facility care adds $217 per day for days 21 to 100. These are the numbers a supplement policy is built to absorb.

Medigap policies are standardized by federal rule and sold under letter names (Plan A, G, N, and others). Every insurer selling a given letter must offer the same core benefits for that letter, so a Plan G from one company covers the same things as a Plan G from another. What differs is price and service, not the benefit list. There is also a high-deductible version of some plans; in 2026, the CMS-set high-deductible amount for Plans G, F, and J is $2,950, meaning you pay costs up to that figure before the policy begins paying.

In short: Medigap absorbs the deductibles and the uncapped coinsurance that Original Medicare leaves to you.

These two are often confused, and choosing between them shapes how the rest of your coverage works. Medigap supplements Original Medicare: you keep Part A and Part B, and the policy pays alongside them. Medicare Advantage (Part C) replaces the way you receive Original Medicare by bundling it into a private plan, usually with a network and often with extra benefits built in.

You cannot hold both at the same time. If you enroll in a Medicare Advantage plan, a Medigap policy cannot pay your share of costs, so the two are mutually exclusive by design. The trade-off comes down to structure. Medigap tends to offer broad provider access and predictable cost-sharing, with a monthly premium on top of your Part B premium. Medicare Advantage often carries a low or $0 plan premium but uses networks, referrals, and prior authorization, and it caps your annual spending through a maximum out-of-pocket limit (MOOP) rather than by paying down each bill.

That MOOP is worth understanding if you are weighing the alternatives. In 2026, the federal in-network MOOP cap for Medicare Advantage is $9,250, and plans may set lower limits. According to KFF, the 2026 enrollment-weighted average in-network MOOP is $5,421. Original Medicare, by contrast, has no such cap on its own, which is precisely the gap Medigap is meant to close.

In short: Medigap pays alongside Original Medicare; Medicare Advantage replaces how you get it, and you cannot use both together.

Timing is the single most consequential decision in supplemental Medicare insurance, because your health can affect both whether you get a policy and what you pay. The one guaranteed-issue Medigap window is six months long, and it starts the month you are both 65 and enrolled in Part B. During this Medigap open enrollment period, insurers must sell you any policy they offer at the best available rate regardless of your health history. They cannot turn you down or charge you more for pre-existing conditions.

Miss that window and the rules change. Outside of it, in most states an insurer can use medical underwriting: reviewing your health, and potentially declining you or raising your premium. That is why the six-month period carries so much weight. It is not a deadline for enrollment in the abstract; it is the moment your bargaining position is strongest.

This window is separate from your Initial Enrollment Period (IEP) for Medicare itself. The IEP is seven months: the three months before your birthday month, your birthday month, and the three months after. Enrolling in Part B during your IEP is what sets your Medigap clock in motion, so the two fit together but serve different purposes.

In short: your strongest and only guaranteed Medigap window is the six months beginning when you are 65 and on Part B.

Life does not always cooperate with a six-month window, and it is fair to ask what changes afterward. Once your guaranteed-issue period closes, most states let insurers underwrite applications, so approval and pricing depend on your health. Some people apply years later without trouble; others find their options narrowed. There is no penalty for a late Medigap application the way there is for late Part B or Part D, but the loss of guaranteed issue is the real cost.

A handful of states offer broader access, and the protections differ in kind rather than forming a single flat list. New York and Connecticut require year-round guaranteed issue. Washington lets enrollees switch from one plan to a comparable one. A group of birthday-rule states, including California and Oregon, gives an annual window tied to your birthday during which you can change policies, with widely varying rules; New Mexico's version takes effect in January 2027. Because these categories work so differently, the rules where you live matter more than any general summary.

If your later options feel limited, that is a good moment to talk through the full picture rather than guess. To find out more about coverage, please contact us to discuss plan options.

In short: after your open enrollment window closes, most states allow underwriting, though a few offer year-round or annual access.

A supplement policy is focused, and knowing its edges prevents surprises. Medigap does not include prescription drug coverage. For that you add a standalone Part D plan, and it pays to do so on time: going 63 or more days without creditable drug coverage after your Initial Enrollment Period triggers the Part D late-enrollment penalty, which adds 1% of the national base beneficiary premium for each full month you went without, permanently.

Part D itself has improved considerably. In 2026, out-of-pocket spending on covered Part D drugs is capped at $2,100 for the year; once you hit that ceiling, covered drugs cost $0 for the rest of the year. No Part D plan may set a deductible above $615 in 2026, and many set a lower amount or none at all.

Medigap also does not pay for routine dental, vision, hearing aids, or long-term custodial care. It will not cover the 20% coinsurance on services Medicare itself does not approve. One useful detail on hearing: since January 2023, Medicare beneficiaries may see an audiologist for certain non-acute hearing assessments without a physician order, once every 12 months, though this applies to the diagnostic visit only and never to hearing aids.

In short: Medigap fills Medicare cost gaps but excludes drugs, dental, vision, hearing aids, and custodial care.

Medigap premiums vary by the plan letter you choose, your age, where you live, and how the insurer prices its policies, so no single figure applies to everyone. A more comprehensive letter costs more per month but leaves less for you to pay at the point of care; a leaner letter or a high-deductible version lowers the premium and shifts more risk back to you.

Separate from your Medigap premium, you still pay your Part B premium. In 2026, the standard Part B premium is $202.90 per month. Higher-income beneficiaries pay more through an income-related monthly adjustment amount (IRMAA). In 2026, IRMAA begins above $109,000 in modified adjusted gross income for a single filer and $218,000 for a married couple filing jointly. Above those lines, you pay progressively more through income-based tiers, plus a parallel surcharge on Part D. IRMAA uses a two-year lookback, so 2026 premiums are based on your 2024 income, and it works as a cliff: one dollar over a threshold moves you into the full next tier.

If a life-changing event such as retirement or the death of a spouse has lowered your income, you can ask the Social Security Administration to use more recent figures by filing form SSA-44. You can also request reconsideration of an IRMAA determination within 60 days of receiving the notice.

In short: Medigap pricing depends on plan and location, and your separate Part B premium may rise with income through IRMAA.

The most reliable approach is to sort your priorities before comparing letters. Decide how much predictability you want at the point of care versus how much monthly premium you are willing to carry. Consider how often you travel or see specialists, since Medigap's broad provider access is one of its defining features. Confirm that you have a Part D plan lined up, because Medigap will not cover drugs. And weigh your timing honestly against that six-month guaranteed-issue window, which is where your leverage is greatest.

Because plan pricing and availability are specific to your situation and your zip code, comparisons only become useful once they are grounded in your actual options. Speak with a licensed insurance agent about your plan options. There is no cost to you.

In short: rank predictability, access, and timing first, then compare standardized letters against your own needs.