Original Medicare covers a lot, but it doesn't cover everything. Deductibles, copays, coinsurance, and excess charges can add up to thousands of dollars a year in out-of-pocket costs. That's where Medicare Supplement insurance — commonly called Medigap — comes in. These standardized private insurance plans fill the "gaps" that Original Medicare leaves behind.

With 10 different Medigap plan types available in most states, choosing the right one can feel overwhelming. This guide breaks down the most popular options, explains what each plan covers, and helps you decide which Medicare Supplement plan makes the most sense for your health needs and budget in 2026.

How Medicare Supplement Plans Work

Medigap plans work alongside Original Medicare (Parts A and B). You pay your Part B premium to the government as usual, plus a separate monthly premium to a private insurer for the Medigap plan. When you receive medical care, Medicare pays its share first, and then your Medigap plan covers some or all of the remaining costs — depending on which plan letter you chose.

A critical thing to understand: Medigap plans are standardized by the federal government. A Plan G from Aetna covers exactly the same benefits as a Plan G from Mutual of Omaha or Blue Cross Blue Shield. The only differences between companies are price, customer service, and financial stability. This makes comparison shopping straightforward — once you pick a plan letter, you just need the cheapest rate from a reputable insurer.

The Most Popular Plans: G, N, and F

Plan G: The Best Overall Choice for Most People

Plan G has become the gold standard of Medigap coverage since Plan F was closed to new enrollees in 2020. It covers nearly everything: Part A coinsurance and hospital costs, Part B coinsurance, the first three pints of blood, skilled nursing facility coinsurance, Part A hospice coinsurance, 80% of foreign travel emergency care, and Part B excess charges. The only thing Plan G doesn't cover is the annual Part B deductible, which is $257 in 2026.

In practical terms, once you pay that $257 deductible each year, a Plan G policy pays for virtually all of your remaining out-of-pocket costs. Monthly premiums for Plan G typically range from $120 to $250 depending on your age, location, gender, and tobacco use. For most enrollees, this is the sweet spot of comprehensive coverage at a reasonable price.

Plan N: The Budget-Friendly Alternative

Plan N covers the same core benefits as Plan G but with two key differences: it doesn't cover Part B excess charges, and it requires small copays for certain services — up to $20 for office visits and up to $50 for emergency room visits that don't result in an inpatient admission. These copays are relatively minor for most people.

The trade-off is a noticeably lower premium. Plan N typically costs $30 to $70 less per month than Plan G from the same insurer. Over a year, that adds up to $360 to $840 in savings. For healthy enrollees who don't visit the doctor frequently and live in a state where most doctors accept Medicare assignment (meaning they don't charge excess fees), Plan N offers strong value.

Plan F: Still Available If You Qualified Before 2020

Plan F was once the most popular Medigap plan because it covers everything — including the Part B deductible that Plan G leaves out. However, Plan F was closed to anyone who became newly eligible for Medicare on or after January 1, 2020. If you were already enrolled in Plan F or became Medicare-eligible before that date, you can keep it. But be aware that Plan F premiums are rising faster than Plan G premiums because no new, younger enrollees are entering the Plan F risk pool.

When to Enroll: The Open Enrollment Window

Your Medigap Open Enrollment Period is the single most important enrollment window in all of Medicare. It starts the month you turn 65 and are enrolled in Part B, and it lasts exactly six months. During this window, insurance companies must sell you any Medigap plan they offer at the standard price, regardless of your health history. They cannot charge more for pre-existing conditions or deny you coverage.

Once this window closes, insurers in most states can use medical underwriting. That means they can deny you coverage or charge higher premiums based on health conditions. Some states offer additional protections — Connecticut, Massachusetts, Maine, and New York require guaranteed-issue rights year-round — but in most of the country, missing your open enrollment window can be costly or even make getting a Medigap plan impossible.

How Much Do Medigap Plans Cost in 2026?

Medigap premiums vary significantly based on where you live, your age, and which insurer you choose. Here are typical monthly premium ranges for 2026:

  • Plan G — $120 to $250/month for a 65-year-old, higher in metro areas and coastal states
  • Plan N — $85 to $190/month for a 65-year-old
  • Plan F — $150 to $320/month (existing enrollees only, premiums trending upward)
  • High-Deductible Plan G — $30 to $75/month with a $2,800 annual deductible before benefits kick in

Insurers use three pricing methods: community-rated (same price regardless of age), issue-age-rated (price based on your age at enrollment, never increases due to age), and attained-age-rated (price increases as you get older). Community-rated and issue-age-rated plans cost more upfront but save money in the long run. Most plans on the market are attained-age-rated, so expect gradual premium increases over time.

Medigap vs. Medicare Advantage: Which Is Right for You?

The biggest decision for Medicare beneficiaries isn't which Medigap plan to buy — it's whether to go with Medigap at all versus a Medicare Advantage plan. Medicare Advantage (Part C) plans often have low or zero premiums and include drug coverage, but they use provider networks and require referrals. Medigap plans have higher premiums but let you see any doctor who accepts Medicare, anywhere in the country, with minimal out-of-pocket costs.

Medigap tends to be the better choice for people who travel frequently, want complete freedom to choose doctors, have chronic health conditions requiring regular specialist visits, or simply prefer the predictability of knowing almost all costs are covered. Medicare Advantage can be a better fit for healthy people on a tight budget who are comfortable staying within a provider network.

Tips for Choosing the Right Plan

  • Don't wait — enroll during your Medigap Open Enrollment Period. Waiting can cost you thousands or leave you uninsurable.
  • Compare at least 5 insurers — because benefits are identical within each plan letter, the cheapest reputable insurer is genuinely the best choice.
  • Check the pricing method — ask whether the plan is community-rated, issue-age-rated, or attained-age-rated. This affects your costs over time more than the starting premium.
  • Consider Plan N if you're healthy — the savings over Plan G can be substantial, and the copays are minor for most people.
  • Remember you'll need separate drug coverage — Medigap plans don't include prescription drugs. You'll need a standalone Part D plan.