What is Medigap?
A Medigap policy is supplemental insurance sold by private companies that helps pay for costs not covered by Original Medicare (Parts A and B). These costs include:
- Part A hospital deductible ($1,676 per benefit period in 2026)
- Part B coinsurance (the 20% you pay after your deductible)
- Part A coinsurance for extended hospital stays
- Skilled nursing facility coinsurance
- Part B excess charges (if a doctor charges more than the Medicare-approved amount)
- Foreign travel emergency care (up to plan limits)
Important: Medigap only works with Original Medicare. If you have a Medicare Advantage plan (Part C), you cannot use a Medigap policy. Medicare Advantage plans have their own built-in cost protections, including an annual out-of-pocket maximum.
Medigap plan letters
Medigap policies are standardized by the federal government and identified by letters. Each letter covers a specific set of benefits. In Colorado, the most common plans are:
| Plan | Coverage highlights | Popularity |
|---|---|---|
| Plan G | Covers everything except the Part B deductible ($257 in 2026). The most comprehensive plan available to new enrollees. | Most popular |
| Plan N | Similar to Plan G but with small copays for some office visits ($20) and ER visits ($50). Lower premiums than Plan G. | Popular budget choice |
| High-deductible G | Same as Plan G but you pay a $2,870 deductible before the plan pays. Much lower premiums. | Cost-conscious choice |
| Plan A | Basic benefits — covers Part A coinsurance, Part B coinsurance, and first 3 pints of blood. No extras. | Less common |
Note: Plan F is no longer available to people who became newly eligible for Medicare on or after January 1, 2020. If you had Plan F before that date, you can keep it.
Medigap costs in Colorado
Medigap premiums vary significantly by insurance company, your age, your ZIP code, and your gender. In Colorado, here are approximate monthly ranges:
| Plan | Approximate monthly range (age 65) |
|---|---|
| Plan G | $120 – $250/month |
| Plan N | $85 – $180/month |
| High-deductible Plan G | $30 – $70/month |
These are estimates. Actual premiums depend on the carrier, your specific location in Colorado, and how the company prices its policies (issue-age, attained-age, or community-rated).
Pricing method matters: Issue-age policies base your premium on the age you were when you bought the policy — they don't increase as you age (though they may increase for inflation). Attained-age policies start lower but increase as you get older. Ask about the pricing method before you buy.
When to enroll
Your Medigap open enrollment period is the single most important window for purchasing a supplement policy. It starts the month you turn 65 and are enrolled in Part B, and lasts 6 months.
During this window:
- Insurance companies must sell you any Medigap policy they offer in Colorado
- They cannot charge more or deny coverage based on health conditions
- They cannot impose waiting periods for pre-existing conditions
After this window closes, Colorado insurers can use medical underwriting. This means they can deny you coverage or charge higher premiums based on your health history.
Colorado Medigap rules
Colorado follows federal Medigap standardization rules, meaning Plan G from one company covers exactly the same benefits as Plan G from another. The only differences are price and customer service.
- Guaranteed issue rights — Colorado provides guaranteed issue rights in certain situations, such as losing employer coverage or if your Medicare Advantage plan leaves your area.
- Free-look period — You have 30 days to review your new Medigap policy. If you're not satisfied, you can return it for a full refund.
- Rate increases — Insurers must file rate increases with the Colorado Division of Insurance. You can check filed rates at doi.colorado.gov.
Medigap vs. Medicare Advantage
This is one of the biggest decisions in Medicare. Here's a quick comparison:
| Medigap + Original Medicare | Medicare Advantage | |
|---|---|---|
| Monthly cost | Part B premium + Medigap premium + Part D premium | Part B premium + MA premium (often $0) |
| Out-of-pocket costs | Very low — Medigap covers most cost-sharing | Copays and coinsurance per service, up to annual max |
| Doctor choice | Any doctor that accepts Medicare, nationwide | Must use plan network (HMO) or pay more out-of-network (PPO) |
| Extra benefits | None — add dental, vision separately | Often includes dental, vision, hearing, fitness |
| Best for | People who want predictable costs and broad provider choice | People who want lower premiums and extra benefits |