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Federal Medigap Open Enrollment Period rules
Under federal law (42 U.S.C. § 1395ss, also known as Section 1882 of the Social Security Act), every Medicare beneficiary gets a one-time, 6-month Medigap Open Enrollment Period. During this window, federal guaranteed-issue rights apply. Outside of it, in most states, insurers may medically underwrite and either deny or surcharge.
When does my federal OEP open?
Your federal 6-month Medigap OEP automatically begins the first calendar month in which you are both:
- Age 65 or older, AND
- Enrolled in Medicare Part B
For most beneficiaries, both conditions become true simultaneously: they enroll in Part B during their Medicare Initial Enrollment Period around their 65th birthday, and the federal OEP opens that month. For beneficiaries who delay Part B (because they have employer coverage, TRICARE, or other qualifying coverage), the federal OEP starts the month they finally enroll in Part B at age 65+.
How long does it run?
Six full calendar months. The window runs from the first day of the anchor month through the last day of the sixth month. Once the OEP closes, the federal guaranteed-issue right is gone (subject to the state-specific protections in your state and the federal qualifying-event protections described below).
What does “guaranteed issue” mean during my federal OEP?
During your federal 6-month Medigap OEP, federal law forbids insurers from:
- Denying you a Medigap policy based on your health
- Charging you a higher premium based on your health, claims history, or pre-existing conditions
- Requiring medical underwriting
Insurers may apply a 6-month pre-existing condition look-back: federal rules permit an insurer to delay coverage of a pre-existing condition for up to 6 months if the condition was treated or diagnosed in the 6 months before your Medigap policy starts — unless you had at least 6 months of prior creditable coverage with no gap longer than 63 days. With creditable coverage, the look-back is reduced or eliminated.
What if my federal OEP has already closed?
Two paths can re-open a guaranteed-issue Medigap window:
- Federal qualifying-event protections. Loss of group employer coverage, Medicare Advantage trial-right disenrollment, MA plan termination, certain Medicaid transitions, insurer bankruptcy. Read the qualifying-events list →
- State-specific protections beyond the federal floor. Continuous-GI states (CT, ME, MA, NY) require year-round or annual GI. Birthday-rule states (CA, OR) allow annual switching without underwriting. Structural-exception states (MA, MN, WI) operate distinct plan structures. See state protections →
If neither path applies, in most states, insurers may now medically underwrite, deny, or charge a higher premium based on your health. This is a real consequence of letting the federal OEP close; it’s also fact-specific, and your state SHIP counselor can confirm what applies to you.
Federal Medigap statute (42 U.S.C. § 1395ss / Section 1882 SSA) and pre-existing-condition look-back rule
Last verified:Source:medicare.gov — When can I buy a Medigap policy?
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