Medicare in Missouri
May 20, 2026
Missouri Medicare quick facts (2026)
- Beneficiaries: Roughly 1.3 million Missourians are enrolled in Medicare.
- Active Advantage carriers: UnitedHealthcare, Humana, Aetna, Anthem Blue Cross Blue Shield, Cigna, WellCare, and others.
- State Medicaid program: MO HealthNet — relevant for dual-eligible coordination through D-SNPs.
- State quirk: Missouri's Anniversary Rule applies to Medigap only — Advantage changes still follow the federal calendar.
Common Missouri Medicare questions
Q: Can I switch Medigap plans in Missouri without underwriting?
A: Yes — under the Missouri Anniversary Rule. For 30 days starting on the anniversary of your Medigap policy, you can switch to the same lettered plan (e.g., Plan G to Plan G) with a different carrier without health underwriting. The federal 6-month Medigap Open Enrollment Period at age 65 also applies.
Q: Does the Missouri Anniversary Rule let me change plan letters?
A: No — the rule covers same-plan-letter carrier switches. Moving from, say, Plan G to Plan N typically requires underwriting outside of federal guaranteed-issue triggers.
Q: When can I enroll in Medicare in Missouri?
A: Federal calendar — Initial Enrollment Period around your 65th birthday; Annual Enrollment Period October 15 – December 7, 2026.
Q: What's MO HealthNet?
A: MO HealthNet is Missouri's Medicaid program. Dual-eligibles (Medicare + MO HealthNet) may qualify for D-SNPs.
Run the numbers for your situation: enrollment calculator · IRMAA calculator · Part D cost calculator.
Medicare in Missouri — plans and how to compare.
What Missouri residents should know about Medicare Advantage, Medicare Supplement, and Part D — and how plan availability differs in Missouri.
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Medicare basics in Missouri
Medicare is a federal program, so the core rules are the same in Missouri as everywhere else — but the specific plans available, premiums, and carrier networks vary by ZIP code and county.
Most Missouri residents become eligible at 65 through Social Security. See eligibility for full rules.
For the 7-month enrollment window timeline, see Turning 65.
What Missouri residents typically compare
- Medicare Advantage — Many Missouri counties have 20-50+ Advantage plans. Plans, premiums, and extras vary by county.
- Medicare Supplement (Medigap) — Plans are federally standardized but premium pricing and underwriting rules vary by state.
- Part D prescription drug plans — Available statewide but formularies and preferred pharmacies differ by plan.
See Advantage vs. Supplement for the side-by-side framework.
Missouri timing rules
The federal Medigap Open Enrollment window is the same everywhere — 6 months starting the month you turn 65 AND have Part B. During that window, no medical underwriting.
Outside that window, most states (including Missouri unless otherwise noted) allow Medigap carriers to use medical underwriting. Check Missouri's State Health Insurance Assistance Program (SHIP) for current state-specific rules.
How to compare plans in Missouri
- Confirm your ZIP — plans differ within Missouri by county
- List your prescriptions and check each on the plan's formulary
- Confirm your doctors are in-network
- Compare premium + deductible + maximum out-of-pocket
- Check star ratings for plans you are weighing
- Ask about prior authorization requirements (common on Advantage)