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Medigap Explained: A Full Guide to Medicare Supplement Insurance

Discover how Medigap (Medicare Supplement) policies function, what they cover, and how they can lower your out-of-pocket expenses.

Published on October 30, 2025

Medigap, also called Medicare Supplement insurance, is private health coverage built to fill the "gaps" left by Original Medicare. These policies help cover out-of-pocket expenses that Medicare Part A and Part B do not pay in full.

How Medigap Functions

When you carry both Original Medicare and a Medigap policy, Medicare pays its portion of covered healthcare costs first. Your Medigap policy then covers its share of the remaining approved expenses, such as copayments, coinsurance, and deductibles.

Here are the essential details about Medigap:

  • Medigap policies are offered by private insurance companies licensed in your state
  • Plans are standardized by the federal government, so each plan letter (A, B, C, D, F, G, K, L, M, N) provides the same benefits regardless of which insurer sells it
  • You must be enrolled in Original Medicare (Parts A and B) to buy a Medigap policy
  • Each Medigap policy covers only one individual; spouses must obtain separate plans
  • You pay a monthly premium to the Medigap insurer on top of your Part B premium

What Medigap Pays For

Depending on which plan you select, Medigap policies may cover:

  • Part A coinsurance and hospital expenses beyond what Medicare pays
  • Part B coinsurance or copayments
  • Part A and Part B deductibles (varies by plan)
  • Part B excess charges (amounts that exceed Medicare-approved rates)
  • Skilled nursing facility coinsurance
  • Foreign travel emergency care (up to plan limits)
  • Blood (first three pints per year)

What Medigap Does Not Pay For

Medigap policies do not cover:

The Ideal Time to Purchase Medigap

Your Medigap Open Enrollment Period is the most advantageous time to buy a policy. This six-month window starts the month you are 65 or older and enrolled in Medicare Part B. During this period:

  • Insurance companies cannot turn you down for coverage
  • They cannot charge you more because of pre-existing health conditions
  • You have guaranteed issue rights to any Medigap plan available in your state

Once this window closes, insurers may apply medical underwriting, which could lead to higher premiums or coverage denial based on your health history.

Is Medigap the Right Choice for You?

Medigap is frequently a strong option for individuals who want predictable healthcare expenses, visit doctors often, or prefer the freedom to see any Medicare-accepting provider nationwide without network restrictions. If minimizing out-of-pocket costs and preserving broad provider access are important to you, a Medigap policy is well worth exploring.

This content is for educational purposes only and does not constitute a recommendation of any specific Medicare plan. Benefits, costs, and availability vary by plan and location. For complete information about your Medicare options, visit Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), TTY: 1-877-486-2048, available 24 hours a day, 7 days a week.