Original Medicare (Parts A and B) is a solid foundation, but it leaves significant out-of-pocket exposure. There is no limit to what you could pay in a single year for hospital stays, specialist visits, or skilled nursing. Medicare Supplement insurance — formally known as Medigap — is designed to cover those costs, giving seniors predictable, manageable healthcare expenses.
What Is a Medicare Supplement Plan?
A Medigap policy is sold by private insurance companies but standardized by the federal government. Every insurer must offer the same benefits for a given plan letter — so Plan G from one company covers the same services as Plan G from another. The only difference is the monthly premium and the quality of customer service.
Medigap policies work alongside Original Medicare. When you receive care, Medicare pays its share first, then your Medigap policy picks up some or all of the remainder. Most plans cover the 20% coinsurance that Medicare Part B leaves behind after you see a doctor or specialist.
Plan F: The Most Comprehensive (But Restricted)
Plan F was historically the most popular Medigap option because it covers nearly every out-of-pocket cost: Part A deductible, Part B deductible, Part B excess charges, coinsurance for skilled nursing, and foreign travel emergency care. However, Plan F is no longer available to people who became eligible for Medicare on or after January 1, 2020. If you were already enrolled before that date, you can keep or purchase Plan F. For everyone else, Plan G is now the gold-standard equivalent.
Plan G: The New Gold Standard
Plan G covers everything Plan F covers, with one exception: the Part B deductible (currently $240 per year in 2026). Once you meet that annual deductible out-of-pocket, Plan G covers 100% of Medicare-approved costs for the rest of the year. For most seniors, the premium savings of Plan G versus Plan F more than offset that $240 deductible, making Plan G the better financial choice.
Plan G also includes coverage for Part B excess charges — the extra amount some doctors charge above the Medicare-approved rate. If you see specialists who do not accept Medicare assignment, this protection can save you hundreds or even thousands of dollars annually.
Plan N: The Budget-Conscious Option
Plan N typically costs less than Plan G but requires small copays: up to $20 for doctor visits and up to $50 for emergency room visits that do not result in an inpatient admission. It does not cover Part B excess charges. Plan N is a good fit for seniors who are generally healthy, see fewer specialists, and want lower monthly premiums while still having solid coverage for hospitalizations and major expenses.
When to Enroll: Open Enrollment Is Your Best Window
The best time to buy a Medigap policy is during your six-month Medigap Open Enrollment Period, which begins the first month you are 65 or older and enrolled in Medicare Part B. During this window, insurers cannot deny you coverage or charge higher premiums based on pre-existing conditions. Outside of this window, you may be subject to medical underwriting, which can result in higher premiums or outright denial.
How Much Does Medigap Cost?
Monthly premiums vary widely based on the plan letter, your age, where you live, your gender, and whether you smoke. For a 65-year-old woman in a mid-sized city, Plan G premiums typically range from $110 to $200 per month. Plan N runs roughly 20 to 30% less. Shopping and comparing multiple carriers is essential — the same Plan G coverage can differ by $50 to $80 per month between insurers in the same zip code.
Key Questions to Ask Before Choosing
- Does the insurer use community rating (same price for all ages) or attained-age rating (price increases as you age)?
- What is the company's financial strength rating from AM Best?
- Are there household discounts if your spouse also enrolls?
- Does the plan cover foreign travel emergencies if you travel internationally?
- What is the average annual rate increase history for this insurer?
Choosing the right Medicare Supplement plan can save you thousands of dollars over your retirement years. A licensed Medicare specialist can compare plans in your ZIP code, explain the pricing structures, and help you enroll during the right window — all at no cost to you.
