3.2 Michigan Medicare Supplement (Medigap) Regulations

Key Takeaways

  • The Medigap open enrollment period lasts 6 months and begins the first month you are both age 65 or older and enrolled in Medicare Part B.
  • During open enrollment, Medigap is guaranteed issue—no underwriting, no pre-existing condition exclusion, and no health-based surcharge.
  • Outside open enrollment (without a guaranteed-issue right), insurers may impose up to a 6-month pre-existing condition look-back and exclusion.
  • Michigan does NOT have a 'birthday rule' allowing annual plan switching; that exists in states such as California and Oregon.
  • Medigap plans are standardized as Plans A–N; Plans C and F are closed to anyone first Medicare-eligible on or after January 1, 2020.
Last updated: June 2026

The 6-Month Open Enrollment Period

Medicare Supplement (Medigap) policies fill gaps in Original Medicare—deductibles, coinsurance, and copays. Michigan applies the federal NAIC (National Association of Insurance Commissioners) standardized framework with state consumer protections.

The Medigap open enrollment period (OEP) is the single most-tested fact in this section. It lasts 6 months and begins on the first day of the month in which you are both (1) age 65 or older AND (2) enrolled in Medicare Part B.

During this 6-month window the applicant has three powerful protections:

  • Guaranteed issue — the insurer must accept the applicant regardless of health.
  • No pre-existing condition exclusion if the applicant had prior creditable coverage with no gap over 63 days.
  • No health-based rate-up — the applicant pays the same rate as a healthy person of the same age.

Worked example: Maria turns 65 on April 14 and enrolls in Part B effective April 1. Her Medigap OEP runs April 1 through September 30. If she applies in August, she cannot be turned down or surcharged for her diabetes. If she waits until November (after the OEP), the insurer may medically underwrite her application and decline it.

Trap — the missing-Part-B trap: The OEP will not start until the applicant has Part B. Someone who delays Part B (because of active employer coverage) does not waste the OEP—it simply starts later, when Part B begins.

No Birthday Rule in Michigan

Some states (California, Oregon, Idaho, Nevada) give beneficiaries an annual birthday rule window to switch to an equal-or-lesser Medigap plan with no underwriting. Michigan has no birthday rule. Outside the OEP and absent a guaranteed-issue trigger, a Michigan beneficiary who wants to change Medigap plans must pass medical underwriting—and can be declined or surcharged. Expect at least one question testing whether Michigan has this rule; the answer is no.

Guaranteed-Issue Rights Outside the OEP

Michigan adopts the federal guaranteed-issue (GI) triggers. When one occurs, the applicant generally has 63 days to buy certain Medigap plans without underwriting.

Triggering eventGuaranteed-issue right
Employer/retiree group coverage endsBuy Medigap within 63 days
Medicare Advantage (MA) plan leaves the area or stops serving youReturn to Medigap
Your Medigap insurer becomes insolventSwitch to a comparable plan
You dropped Medigap to try an MA plan (first time)Trial right (see below)
You lose Medicaid eligibilityBuy Medigap

The 12-Month MA Trial Right

If a beneficiary drops a Medigap policy to join Medicare Advantage for the first time, they have 12 months to change their mind. Within that year they may return to their prior Medigap plan (or, if unavailable, a comparable plan from the same or another insurer) on a guaranteed-issue, no-health-question basis. This protects newcomers from being trapped in MA.

Pre-Existing Condition Rules

SituationPre-existing condition treatment
During the 6-month OEPNo exclusion if prior creditable coverage; otherwise up to 6-month exclusion
With a guaranteed-issue rightNo exclusion permitted—ever
Outside OEP, no GI rightUp to 6-month look-back and 6-month exclusion allowed

The look-back means the insurer may exclude coverage for a condition diagnosed or treated within 6 months before the policy's effective date, for up to 6 months. Creditable coverage (prior group, COBRA, Medicaid, marketplace) with no gap over 63 days erases this waiting period.

Standardized Plans and Rating

PlanNotable feature
ACore/basic benefits only
BCore + Part A deductible
CComprehensive — closed to those newly eligible 1/1/2020+
DLike C without Part B excess charges
FMost comprehensive — closed to those newly eligible 1/1/2020+
GLike F but excludes the Part B deductible
K / L50% / 75% cost-sharing with an out-of-pocket maximum
NCopays for some office and ER visits

Because Plans C and F cover the Part B deductible, they were closed to anyone first eligible for Medicare on or after January 1, 2020. Those people now choose Plan G as the richest available option.

Michigan permits three rating methods: attained-age (premium rises with current age), issue-age (set by age at purchase), and community-rated (same premium for all ages). Rate changes must be filed with DIFS; rates may not vary by health during the OEP. Producers must complete Medicare-related training, use the approved Outline of Coverage, and may not falsely compare Medicare to Medicaid.

What Medigap Does and Does Not Cover

A Medigap policy pays secondary to Original Medicare—it fills gaps such as the Part A hospital deductible, Part A and Part B coinsurance, and the first three pints of blood. It does not add new categories of benefits, and this is a heavily tested distinction:

Medigap generally coversMedigap does NOT cover
Part A hospital deductible and coinsuranceOutpatient prescription drugs (need Part D)
Part B coinsurance / copaysLong-term custodial care
First three pints of bloodRoutine dental, vision, hearing aids
Skilled nursing facility coinsuranceEyeglasses, private-duty nursing

Trap: A Medigap policy cannot pay the deductible or copays of a Medicare Advantage (Part C) plan. It is illegal for a producer to sell Medigap to someone enrolled in Medicare Advantage unless that person is disenrolling and returning to Original Medicare. Likewise, Medigap is individual coverage—one policy per person, so a married couple needs two separate policies.

Marketing and Disclosure Rules

Michigan and the NAIC model impose strict anti-abuse rules. Producers may not:

  • Sell a beneficiary more than one Medigap policy (no stacking/duplication).
  • Use high-pressure tactics or fear-based sales scripts.
  • Engage in twisting (misrepresenting to replace coverage) or churning (replacing the insured's own existing Medigap to earn a new commission).
  • Claim a Medigap plan is a Medicare-endorsed or government product.

Replacement of an existing Medigap policy requires a signed replacement notice and the insurer must account for any pre-existing condition time already served, so the insured is not penalized twice.

Test Your Knowledge

George enrolls in Medicare Part B effective May 1, the month he turns 65. When does his 6-month Medigap open enrollment period end?

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B
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D
Test Your Knowledge

A Michigan beneficiary wants to switch Medigap plans two years after enrolling, with no qualifying event. What can the insurer do?

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B
C
D
Test Your Knowledge

A beneficiary dropped Medigap to try a Medicare Advantage plan for the first time. How long is the trial right that lets her return to Medigap with guaranteed issue?

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B
C
D
Test Your Knowledge

Outside open enrollment and without a guaranteed-issue right, what is the maximum pre-existing condition exclusion a Michigan Medigap insurer may impose?

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B
C
D