Updated July 9, 2026
Medigap fills the gaps Original Medicare leaves, the deductibles and coinsurance that beneficiaries would otherwise pay out of pocket. Plans are standardized, so the same letter means the same coverage at every insurer. Price is the variable that matters when shopping.
How Medigap works
You keep Original Medicare and layer a Medigap policy on top. The policy pays your share of covered costs, so billing surprises become rare. You still need a separate Part D drug plan, and you continue paying your Part B premium alongside the Medigap premium.
Plan G vs Plan N vs F
Plan G is the most common choice for new enrollees. It covers nearly everything except the annual Part B deductible. Plan N costs less per month but adds small copays at some visits. Plan F (now closed to people who became Medicare-eligible in 2020 or later) covered everything including the deductible. The plan comparison tool lays them out side by side.
What it costs
Because coverage is federally standardized, price is the main differentiator. Monthly premiums typically run $100 to $300, depending on plan, age, and state. Shopping the same letter across multiple insurers is the best strategy; the lowest-priced reputable carrier for a given letter generally delivers the same benefits as the most expensive one. Estimate with the cost calculator.
Medigap vs Advantage
Medigap carries a higher monthly premium but makes out-of-pocket costs predictable and lets you use any Medicare-accepting provider nationwide. Medicare Advantage plans often have lower or $0 monthly premiums, but they use networks, apply copays, and can change benefits each year. The Medigap vs Advantage calculator compares total annual cost under both approaches.
The window that matters most
For six months after your Part B coverage starts, you can buy any Medigap plan with no health questions. Miss that window and insurers in most states can deny you or charge more based on your health. The open enrollment calculator shows exactly when your window opens and closes.