Published on September 1, 2025
4 min read
Medicare Supplement Insurance Explained: What It Covers & How to Choose
Medicare covers many healthcare expenses, but it doesn't pay for everything.
Out-of-pocket costs like copayments, deductibles, and coinsurance can add up quickly.
That’s where Medicare Supplement Insurance, also known as Medigap, comes in—it helps cover these extra costs and provides greater financial security.
Choosing the right Medigap plan can be confusing, as there are multiple options with different coverage levels.
This guide will help you understand what Medicare Supplement Insurance covers, how it works, and how to select the best plan for your needs.
What Is Medicare Supplement Insurance?
- A private insurance policy designed to cover costs not paid by Original Medicare (Parts A & B).
- Helps reduce or eliminate expenses like deductibles, copayments, and coinsurance.
- Available to Medicare beneficiaries but does not work with Medicare Advantage plans.
What Does Medicare Supplement Insurance Cover?
Out-of-Pocket Costs from Original Medicare
- Medicare Part A deductible and coinsurance.
- Medicare Part B coinsurance and copayments.
- Excess charges from doctors who don’t accept Medicare’s standard rates.
Hospital and Skilled Nursing Facility Costs
- Extended hospital stays beyond what Medicare covers.
- Skilled nursing facility coinsurance.
Emergency Medical Coverage Abroad
- Some Medigap plans offer coverage for emergency medical services outside the U.
S. - Usually covers up to 80% of foreign emergency costs.
What Medicare Supplement Insurance Does Not Cover
- Prescription drugs (you’ll need a separate Medicare Part D plan).
- Long-term care or custodial care.
- Dental, vision, or hearing services.
Comparing Medicare Supplement Plans
Medigap policies are standardized into different plans labeled A through N.
Each offers a different level of coverage.
Popular Medicare Supplement Plans
- Plan F: Covers all Medicare-approved out-of-pocket costs but is only available to those eligible before 2020.
- Plan G: Similar to Plan F but does not cover the Medicare Part B deductible.
- Plan N: Covers most costs but requires copayments for some doctor visits and ER visits.
How to Choose the Best Medicare Supplement Plan
Assess Your Healthcare Needs
- Consider how often you visit doctors and specialists.
- Determine if you need coverage for foreign travel medical emergencies.
Compare Costs and Premiums
- Premiums vary by plan and provider, so shop around.
- Decide if you prefer a higher monthly premium for lower out-of-pocket costs.
Check Insurance Provider Ratings
- Choose a reputable company with strong customer reviews.
- Look for financial stability and reliable claims processing.
When to Enroll in a Medigap Plan
- The best time to enroll is during your Medigap Open Enrollment Period (6 months after you turn 65 and enroll in Medicare Part B).
- During this time, you cannot be denied coverage or charged higher rates due to pre-existing conditions.