Medicare Supplement Plans in Colorado: What You Need to Know

Colorado’s rapidly growing senior population means more residents than ever are weighing their Medicare options. According to CMS data, the state has more than 900,000 Medicare beneficiaries, and that number rises each year as baby boomers continue aging in. If you are exploring Medicare Supplement plans Colorado has available, you will find a competitive marketplace with strong consumer protections and a solid range of carriers to choose from. This guide covers what you need to know to make an informed decision in 2026.

Overview of Medigap in Colorado

Medigap plans in Colorado follow the federal standardization rules, meaning plan letters A through N offer the same core benefits regardless of which insurer sells them. A Plan G sold by one company covers exactly the same gaps in Original Medicare as a Plan G sold by any other company, so you are really comparing price, customer service, and each carrier’s rate-increase history rather than the benefits themselves. The most popular plans among Colorado enrollees are Plan G and Plan N.

Plan G covers all of Original Medicare’s cost-sharing except the annual Part B deductible, which is $283 for 2026 (verify the current figure at Medicare.gov, as it is set each year). Once you pay that deductible, Plan G picks up your Part A and Part B coinsurance, the Part A hospital deductible of $1,736 per benefit period, Part B excess charges, and the first three pints of blood. Plan N covers most of the same costs but asks you to pay copays of up to $20 for some office visits and up to $50 for emergency-room visits that do not lead to an inpatient admission, and it does not cover Part B excess charges — trade-offs that result in lower monthly premiums.

Colorado’s Division of Insurance, part of the Department of Regulatory Agencies (DORA), oversees all Medigap policy filings in the state. The division requires insurers to submit rate filings for approval and provides public access to premium comparison information. This transparency helps consumers compare Medicare Supplement plans Colorado carriers offer without relying solely on agent recommendations. For a detailed look at how all lettered plans differ, see our Medicare Supplement plan comparison.

Plans F and C Are Closed to Newcomers

One rule trips up a lot of new shoppers. Under the federal MACRA law, Medigap Plans C and F — the two plans that covered the Part B deductible — are closed to anyone who first became eligible for Medicare on or after January 1, 2020. If you were already eligible before that date, you can generally still buy or keep those plans; if you became eligible more recently, they are off the table for you. That closure is a big reason Plan G has become the default “comprehensive” choice for newly eligible Coloradans: it is essentially Plan F minus the Part B deductible. Do not spend time chasing a Plan F quote if you aged into Medicare in 2020 or later.

How Medigap Premiums Are Priced (Rating Methods)

Two carriers can sell the identical Plan G yet raise your rate very differently over time, because insurers use one of three rating (pricing) methods defined by the NAIC. Understanding which one a policy uses matters as much as the opening premium:

• Community-rated (no-age-rated): everyone with that plan pays the same base premium regardless of age. Your premium does not go up simply because you get older.
• Issue-age-rated: your premium is based on your age when you first buy the policy and does not rise as you age. Buying earlier locks in a lower base.
• Attained-age-rated: your premium starts lower but increases as you get older. These can look cheapest at 65 and become the most expensive later.

All three methods can still rise with general inflation and medical-cost trends, so ask each carrier which method it uses and request its recent rate-increase history from DORA before you decide. A slightly higher community-rated or issue-age premium today can cost you far less over a 20-year retirement than a low attained-age teaser rate.

Top Carriers and Illustrative Premium Ranges

Colorado benefits from a competitive Medigap market with numerous carriers. Major insurers offering plans in the state include AARP/UnitedHealthcare, Mutual of Omaha, Anthem Blue Cross Blue Shield, Cigna, Aetna, Humana, and several smaller carriers like Manhattan Life and Capitol Life. The presence of multiple carriers drives competitive pricing.

The dollar ranges below are illustrative only and change frequently — treat them as ballpark context, not quotes. For a 65-year-old non-smoking female in the Denver metro area, Plan G monthly premiums in 2026 have commonly fallen roughly in the $125 to $200 range, and Plan N in roughly the $85 to $155 range, but individual carriers price above and below those bands. In areas outside the Front Range, premiums may differ depending on the carrier’s regional pricing. Male premiums are generally 5 to 15 percent higher, and tobacco users can expect a surcharge of about 10 to 25 percent. Always pull live, personalized quotes for your ZIP code and confirm current amounts at Medicare.gov; our Medicare Supplement plans cost article provides further context on pricing factors.

Colorado-Specific Consumer Protections

Colorado has enacted several protections that benefit Medigap shoppers beyond what federal law requires. The state mandates a 30-day free-look period during which you can return a Medigap policy for a full refund if you are not satisfied. Colorado also requires Medigap insurers to offer coverage to Medicare-eligible individuals under 65 who qualify due to disability, though premiums for this group may be higher than standard rates. Because eligibility details and pricing for under-65 enrollees can change, confirm the current rules with the Colorado Division of Insurance.

Colorado also has a state “birthday rule” that gives existing Medigap policyholders an annual window, tied to their birthday, to switch plans without going through new medical underwriting — as long as they move to a plan with the same or fewer benefits (an equal or lesser plan). This is significant because it gives you a yearly opportunity to shop for a lower rate without worrying about health-related denials, a protection only a handful of states offer. The exact length of the window and the precise switching rules have been set and adjusted by state law, so verify the current birthday-rule window and conditions with the Colorado Division of Insurance before you rely on a specific number of days. Do not cancel your existing policy until the new one is approved and in force.

Medicare Advantage vs Medigap in Colorado

Colorado has a robust Medicare Advantage market, particularly along the Front Range. Beneficiaries in Denver, Colorado Springs, Fort Collins, and Boulder typically have many Medicare Advantage plans to choose from, including HMO, PPO, and Special Needs Plans. Many of these plans offer $0 premiums with extras like dental, vision, and hearing coverage. The trade-off is that Advantage plans use provider networks and their own prior-authorization and cost-sharing rules, whereas a Medigap plan pairs with Original Medicare and lets you see any provider that accepts Medicare nationwide.

Beneficiaries in mountain communities and the Western Slope may have far fewer Medicare Advantage options and smaller provider networks. For rural Colorado residents, Original Medicare with a Medigap plan often provides more reliable access to care. The ability to see any Medicare-accepting provider, including specialists at facilities like the University of Colorado Hospital or National Jewish Health, without network restrictions is a major advantage. Our Medigap vs Medicare Advantage guide explores these trade-offs in depth.

Enrollment Rules and Timing

Your Medigap Open Enrollment Period in Colorado begins the first day of the month you are both 65 or older and enrolled in Part B, and it lasts six months. During this one-time window, insurers must sell you any Medigap plan they offer at standard rates without medical underwriting, and they cannot deny you or charge more for pre-existing conditions. This is the single most important enrollment window for Medigap, and missing it can permanently affect your ability to get affordable coverage, because outside of it (and outside a guaranteed-issue situation or the state birthday rule) insurers can use medical underwriting to raise your rate or turn you down.

Colorado’s birthday rule provides an additional annual window for switching between plans, but it does not replicate the full protections of the initial Open Enrollment Period. If you are enrolling in Medicare for the first time, consider purchasing Medigap during your Open Enrollment Period even if you are healthy, because your future health is uncertain and this is your best opportunity to lock in coverage. For free, unbiased enrollment counseling, contact Colorado’s State Health Insurance Assistance Program (SHIP); it has commonly been reached at 1-888-696-7213, but verify the current number before calling.

Part D and Prescription Drug Considerations

If you choose a Medigap plan in Colorado, you will need a separate Medicare Part D plan for prescription drug coverage, because Medigap does not include drug coverage. The state typically offers a wide slate of standalone Part D plans, with monthly premiums varying considerably depending on coverage level and formulary. The most popular plans balance premium cost with formulary breadth and pharmacy network size, so compare each plan against your specific medication list rather than premium alone.

Colorado beneficiaries with limited incomes may qualify for Medicare Extra Help (the Part D Low-Income Subsidy), which can reduce Part D premiums to zero and lower copays to a small set amount per prescription; verify the current copay figures, as they are updated each year. The Colorado Department of Health Care Policy and Financing administers the state Medicaid program (Health First Colorado), which provides additional assistance for dual-eligible beneficiaries who qualify for both Medicare and Medicaid.

Choosing the Right Plan in Colorado

Selecting among Medicare Supplement plans Colorado offers starts with two key decisions: which plan letter and which carrier. For the plan letter, most new enrollees in Colorado choose between Plan G and Plan N. Plan G provides the most comprehensive coverage available to newcomers, with minimal out-of-pocket costs beyond your premium and the annual Part B deductible. Plan N saves roughly $30 to $50 per month on premiums in exchange for small copays and no coverage of Part B excess charges. Because a large majority of Colorado physicians accept Medicare assignment, excess charges are relatively rare, but they are not impossible — factor that into the Plan N decision. For more details on Plan N specifically, see our Plan N guide.

For the carrier, compare at least five quotes, check each company’s rate-increase history and rating method through DORA, and look for available discounts. Household discounts, non-smoker discounts, and electronic-fund-transfer discounts can reduce your premium by roughly 5 to 15 percent. AM Best financial-strength ratings help you assess carrier stability, which matters because you may hold this policy for decades.

Frequently Asked Questions

Does Colorado have a Medigap birthday rule?

Yes. Colorado gives existing Medigap policyholders an annual window, tied to their birthday, to switch to a plan with the same or fewer benefits without new medical underwriting. It is one of the strongest consumer protections available to Colorado Medigap enrollees. Because the exact window length and conditions are set by state law and can change, confirm the current rules with the Colorado Division of Insurance before you switch.

Can I get Medigap in Colorado if I am under 65?

Yes. Colorado requires Medigap insurers to offer policies to Medicare-eligible individuals under 65, including those who qualify due to disability or End-Stage Renal Disease. Premiums may be higher than standard rates for this group, but coverage cannot be denied outright. Verify the current under-65 rules with the Division of Insurance.

What is the cheapest Medigap plan in Colorado?

Plan K and Plan L carry the lowest premiums, but they also cover the least and expose you to more out-of-pocket cost. Among the widely chosen plans, Plan N is consistently less expensive than Plan G. Advertised “cheapest” premiums change constantly and vary by carrier, age, and location, so pull live quotes rather than relying on a fixed figure.

Can I still buy Plan F in Colorado?

Only if you first became eligible for Medicare before January 1, 2020. Plans F and C are closed to anyone who became Medicare-eligible on or after that date. If you are newly eligible, Plan G offers the closest comparable coverage.

How many Medigap carriers are in Colorado?

Colorado has roughly 15 to 20 Medigap carriers actively selling policies, though not every carrier offers every plan letter in every county. The Colorado Division of Insurance maintains a current list of approved carriers and their filings on its website.

Taking Action

Colorado’s competitive Medigap market, combined with the state’s birthday rule and consumer protections, puts beneficiaries in a strong position. Take advantage of these protections by enrolling during your Open Enrollment Period, comparing multiple carriers and their rating methods, and using the birthday rule each year to check for better rates. Whether you opt for Plan G’s comprehensive coverage or Plan N’s lower premiums with small copays, Medicare Supplement plans Colorado residents can access provide genuine financial security. Start your research through the healthcare policy guide, confirm current figures at Medicare.gov, and use Colorado SHIP for free personalized guidance.

Sources

• Medicare.gov — 2026 Medicare costs: Part A hospital deductible $1,736 per benefit period, Part B annual deductible $283, and standard Part B premium $202.90 per month
• Centers for Medicare & Medicaid Services (CMS) / Medicare.gov — Medigap standardization (Plans A-N), Medigap Open Enrollment Period rules, and the closure of Plans C and F to those first eligible on or after January 1, 2020
• Colorado Division of Insurance (DORA) and Colorado State Health Insurance Assistance Program (SHIP) — state Medigap protections, the Colorado birthday rule, free-look period, and under-65 access (verify current windows and contact details)
• National Association of Insurance Commissioners (NAIC) — the three Medigap rating methods (community-rated, issue-age-rated, and attained-age-rated)