PharmSurance Field Guide
What Is Medigap?
A Plain-Language Guide
Medicare Supplement plans fill the gaps Original Medicare leaves behind. Here's what you need to know.

Original Medicare covers a lot — but it leaves behind cost-sharing with no built-in cap on your share of most outpatient costs. Medigap plans are sold by private insurers to cover those gaps. The catch: timing matters enormously.

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How Medigap Works
The basics
The core idea

You keep Original Medicare (Parts A and B). Medigap pays after Medicare pays its share — covering most or all of what's left.

What it covers (varies by plan)
  • Part A hospital coinsurance and extended hospital stays
  • Part B coinsurance (the share you'd otherwise owe)
  • Part B excess charges (billed above Medicare rates)
  • Part A and B deductibles (on some plans)
  • Foreign travel emergency coverage (on some plans)
  • Does NOT include drug coverage — add a separate Part D plan
  • Does NOT work with Medicare Advantage — only Original Medicare
What it costs
  • Plan G (most popular): most comprehensive coverage available to new enrollees
  • Plan N: lower premium, small copays for office visits and ER
  • High-deductible versions available at lower monthly cost
Standardizedsame coverage across every insurer for a given letter
The Enrollment Window
Critical timing — read this carefully
Why this matters so much

You have a 6-month open enrollment window starting the month you turn 65 and are enrolled in Part B. During this window, no insurer can deny you or charge you more due to health conditions.

During your open enrollment window
  • Insurers must sell you any Medigap plan they offer in your state
  • No medical underwriting — health conditions don't affect your eligibility or price
  • This is your best (and often only) chance to get guaranteed coverage
After the window closes
  • Insurers can refuse to sell you a plan based on your health history
  • They can charge you significantly more based on pre-existing conditions
  • Some states have additional protections — check with an advisor
Choosing a Plan
Plan G vs. Plan N — the most common choice
The two most popular options

Plan G is the most comprehensive. Plan N costs less per month but has small copays when you use care.

Plan G
  • Covers everything except the Part B deductible
  • After your deductible, you pay very little for covered care
  • Most popular plan for predictable, comprehensive coverage
Plan N
  • Lower monthly premium than Plan G
  • Small copays for office visits and ER visits that don't result in admission
  • May have Part B excess charges (rare but possible)
  • Good option if you're generally healthy and want to save monthly
At a glance
Is Medigap right for you?
Good fit if...

You want to see any doctor anywhere without network limits, prefer predictable monthly costs over surprise bills, have complex health needs, or travel frequently.

May not be needed if...

You're enrolling in Medicare Advantage (Medigap doesn't work with Advantage plans), or you're comfortable with the built-in cost cap that Advantage plans provide.

Want help choosing the right plan?

A PharmSurance advisor will compare Medigap options in your state and help you decide if it's the right fit — or if Medicare Advantage makes more sense. At no cost to you.

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