If your Missouri Medicare Supplement premium just went up, you may be able to move the exact same coverage to a cheaper company without a single health question.

That right comes from Missouri's Medigap anniversary rule, and Missouri is the only state that gives current Medigap policyholders an annual window to switch insurers without medical underwriting. This guide explains who qualifies, what you can switch to, and the one date that controls your window.

In This Guide

What Missouri's Medigap Anniversary Rule Is

A Medigap policy fills the gaps in Original Medicare, and the benefits for a given plan letter are standardized by federal law. That means one company's Plan G pays the same way as another company's Plan G. The only real difference between two Plan G policies is the price.

In most states, once your one-time federal Medigap Open Enrollment Period ends, an insurer can make you answer health questions before it will sell you a new policy, and it can decline you or charge more based on your health. That is what keeps many people stuck in a policy whose premium keeps climbing.

Missouri changes this. Under Missouri regulation 20 CSR 400-3.650(13), a current Medigap policyholder who terminates their policy within 30 days of that policy's annual anniversary date becomes a guaranteed-issue eligible individual. A guaranteed-issue right means an insurer must sell you the policy and cannot use your health to deny you or raise your rate. So every year, around your anniversary, you get a fresh chance to shop the same coverage to a lower-priced company.

Who Qualifies for the Missouri Medigap Anniversary Rule

The rule is narrow, and three conditions decide whether it applies to you.

  • You must already have a Medigap policy. The anniversary rule is a switching right, not a back door into Medigap. If you have only Original Medicare, or you are on a Medicare Advantage plan, this rule does not let you buy a Medigap policy without underwriting.
  • You must act within 30 days of your policy's anniversary date. The anniversary is the date your current policy first took effect, not your birthday and not a fixed calendar date. Because it is tied to your own policy, every policyholder's window falls at a different time.
  • You must switch to the same plan letter. Moving to a plan with more or fewer benefits is not protected by this rule and may require medical underwriting.

If you are not sure whether you currently hold a Medigap policy or a Medicare Advantage plan, the difference matters here. See Original Medicare vs. Medicare Advantage to confirm which one you have.

What You Can Switch To

The protected move is a like-for-like switch: a Medigap policy of the same plan letter you are most recently enrolled in, offered by any insurer in Missouri. For example, you may move from one company's Plan G to another company's Plan G. No health questions or underwriting may be used for a qualifying same-plan switch, so a clean switch cannot be denied or surcharged for health reasons.

There is one fallback. If your exact plan letter is no longer available because of plan-design changes, the guaranteed-issue choices are Plan A, B, C, F (including high-deductible F), K, or L.

Finding Your Anniversary Date

Your anniversary date is the date your current Medigap policy first took effect. You can find it on your policy declarations page, often labeled as the effective date or issue date, or by calling your current insurer and asking for your policy's effective date. Once you know that date, your switching window opens within 30 days of the same month and day each year.

Because the window is short and timing matters, it helps to start comparing prices before your anniversary arrives so you can move quickly once your window is open.

The Anniversary Rule at a Glance

Item What to Know
Who qualifies A current Missouri Medigap policyholder. You must already hold a Medigap policy.
What you can switch to The same plan letter from any insurer (for example, Plan G to Plan G). Fallback to Plan A, B, C, F, K, or L if your letter is retired.
When Within 30 days of your policy's annual anniversary date, the date your current policy first took effect.
Underwriting None for a qualifying same-plan switch. You cannot be denied or surcharged for your health.
Common mistake Trying to change plan letters, using your birthday instead of your policy anniversary, or assuming it works without already having Medigap.

How to Use It

  1. Confirm you currently hold a Medigap policy and note its plan letter.
  2. Find your policy's effective date. That date sets your anniversary window each year.
  3. Before your anniversary, compare prices from other Missouri insurers for the same plan letter. Free, unbiased help is available from MO SHIP at 1-800-390-3330.
  4. Apply for the new same-letter policy and time your switch so you terminate your current policy within 30 days of your anniversary date. Do not cancel your old policy until your new coverage is confirmed in force.

Frequently Asked Questions

Can I switch from Plan G to Plan N under the anniversary rule?

No. The anniversary rule protects a same-plan-letter switch only, so Plan G to Plan G or Plan N to Plan N. Moving from Plan G to Plan N, or to any plan with more or fewer benefits, is not protected by this rule and may require medical underwriting.

Does this work if I only have Original Medicare?

No. You must already hold a Medigap policy to use the anniversary rule. It is a way to switch your existing Medicare Supplement company, not a way for someone with only Original Medicare or a Medicare Advantage plan to buy Medigap without underwriting.

Is the window based on my birthday?

No. The window is tied to your policy's annual anniversary date, the date your current policy first took effect, not your birthday and not a fixed calendar date. Because it is tied to your own policy, every policyholder's window falls at a different time.

What if my plan letter is no longer sold?

If your exact plan letter is no longer available due to plan-design changes, the guaranteed-issue fallback choices are Plan A, B, C, F (including high-deductible F), K, or L.

How do I know my switch will be guaranteed issue?

The protected window is within 30 days of your policy's anniversary date, for the same plan letter, with no health questions allowed. If you are unsure about timing or which insurers offer your plan letter, call MO SHIP at 1-800-390-3330 for free, unbiased Medicare counseling before you cancel anything.

Learn More

MedicareHow Medigap WorksMedigap (Medicare Supplement) explained: how the standardized A-N plans work, Plan G vs Plan N, closed C and F plans, and the 6-month guaranteed-issue window. MedicareMedicare Plans and Coverage in MissouriMedicare in Missouri for 2026: Parts A and B costs, Medicare Advantage, Part D, Medigap, the SLMB1/SLMB2 savings programs, and free MO SHIP counseling. MedicareMedicare: The National GuideWhat is Medicare? A plain guide to Parts A, B, C, and D, who qualifies, 2026 costs, when to enroll, and what it doesn't cover, with help-paying options. MedicareOriginal Medicare vs. Medicare AdvantageCompare original Medicare vs Medicare Advantage on cost, networks, the $9,250 cap, and switching back. A neutral 2026 side-by-side to help you choose.

If your Missouri Medigap premium has gone up, get free help timing your anniversary switch and comparing same-letter policies at brevy.com.

The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.

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Brevy Care Team

Expert eldercare guidance from Brevy's team of healthcare professionals and researchers.