What are the Medigap rules in Colorado?

Outside your open enrollment period or a federal guaranteed issue right, a Colorado Medigap insurer can ask health questions, and it can decline you or charge more. That is the main reason the first decision at 65 matters so much.

Colorado Medigap rules at a glance

Rule	Colorado	Source
Medigap Open Enrollment	6 months from the month you are 65 and have Part B; no health questions	Medicare.gov
Under 65 with Medicare (disability)	Insurers must sell Medigap; rates may be higher than at 65, with new guaranteed issue rights at 65	Colorado Division of Insurance; NAIC chart
Birthday or anniversary switching rule	None as of May 11, 2026	NAIC chart
Plans sold	Standardized plans A, B, D, G, K, L, M, N and high-deductible G for anyone; Plans C, F and high-deductible F only for people eligible for Medicare before January 1, 2020	Colorado Division of Insurance; Medicare.gov Medigap guide

How Medigap works in Colorado

A Medigap policy sits on top of Original Medicare and pays some or all of what Medicare leaves, such as the 20% Part B coinsurance and the Part A hospital deductible. Plans are standardized by letter, so a Plan G from one company has the same benefits as a Plan G from another; the price, the rate history and the company's service are what differ.

Medigap does not include drug coverage, so most people pair it with a stand-alone Part D plan. Plan G covers everything Original Medicare covers except the Part B deductible ($283 in 2026).

Plans C and F, which also cover the Part B deductible, are closed to anyone new to Medicare on or after January 1, 2020. If you turn 65 in 2026 or 2027, your choices are Plans A, B, D, G, K, L, M and N plus high-deductible G. Only people who were first eligible for Medicare before January 1, 2020 can still buy Plan C, Plan F or high-deductible F, and anyone who already has one can keep it (Medicare.gov, Choosing a Medigap Policy guide).

How Medigap premiums are set, and excess charges

Each insurer decides how it prices a policy, so the same letter can cost very different amounts. The official Medicare.gov guide Choosing a Medigap Policy lists three pricing methods: community rating, where everyone pays the same regardless of age; issue-age rating, based on your age when you buy; and attained-age rating, where the premium rises as you get older. Ask which method a Colorado quote uses, because a low attained-age price at 65 can climb faster than an issue-age price.

A doctor who does not take Medicare assignment can charge up to 15% above the Medicare-approved amount, called the limiting or excess charge (Medicare.gov, Does your provider accept Medicare as full payment). Plan G pays those excess charges and Plan N does not (benefits chart in Choosing a Medigap Policy), which is one reason Plan N usually costs less. If your doctors all accept assignment, the difference may not matter to you.

What changes the answer

Federal guaranteed issue rights can let you buy a Medigap policy without health questions after certain events, for example if your Medicare Advantage plan leaves Colorado, you lose employer retiree coverage, or you try Medicare Advantage for the first time and leave within 12 months. Colorado does not add a yearly birthday window, according to the NAIC chart as of May 11, 2026.

If you are under 65 and on Medicare because of a disability, Colorado insurers must offer you a policy, though the premium may be higher. When you turn 65 you get a new open enrollment period and can shop again.

Worked example: an outpatient year without and with Plan G

Suppose Medicare approves $10,000 of outpatient care in 2026: imaging, a procedure, therapy. On Original Medicare alone you pay the $283 Part B deductible, then 20% of the remaining $9,717, or $1,943.40, for $2,226.40 in total, with no ceiling if the bills keep coming. With Plan G, your share is the $283 deductible and the policy premium.

That protection is why the first purchase matters. Adams County has 59,925 residents aged 65 or older, 11.3% of its population, against 15.6% statewide, per Census estimates for 2020 to 2024; many reach this decision while still working.

What to do next

If you are within 6 months of starting Part B at 65, compare Medigap plans now while no health questions apply. If you are past that window, we can check whether a guaranteed issue right applies before you apply anywhere. Lisa reviews Medigap and Medicare Advantage side by side at the Brighton office.

Related questions

Sources

1. Colorado Division of Insurance: Medicare Supplement Insurance Policies in Colorado (September 2025) Colorado Division of Insurance
2. NAIC: State Medigap rules, birthday rule and coverage for people under 65 (as of May 11, 2026) National Association of Insurance Commissioners
3. Medicare.gov: Ready to buy a Medigap policy? Centers for Medicare & Medicaid Services
4. 2026 Medicare Parts A & B Premiums and Deductibles Centers for Medicare & Medicaid Services
5. U.S. Census Bureau, American Community Survey 2020 to 2024 5-year estimates U.S. Census Bureau
6. Medicare.gov: Choosing a Medigap Policy (official guide) Centers for Medicare & Medicaid Services
7. Medicare.gov: Medigap costs Centers for Medicare & Medicaid Services
8. Medicare.gov: Does your provider accept Medicare as full payment? Centers for Medicare & Medicaid Services

Please note: We do not offer every plan available in your area. Currently we represent 10 organizations which offer 106 products in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options.Headwaters Health and Wealth is not connected with or endorsed by the United States government or the federal Medicare program. Medicare has neither endorsed nor reviewed this information.