Delaying Part B. Protecting Your Medigap Options
Know Before You Delay Part B.
Educational Article Written By:
Justin Tomlin
Licensed Insurance Agent
FL W960118 · GA 3760385
3-minute read
Last Updated:
Disclosure: We do not offer every plan available in your area. Currently we represent 5 organizations which offer 55 products in your area. Please contact Medicare.gov, call 1-800-MEDICARE, or your local State Health Insurance Program (SHIP) for more information on all of your options. Organization and product counts are based on the Gainesville, FL area. Actual plans available may vary based on your ZIP code.
When Your Employer Plan Pays First
Most people become eligible for Medicare at 65. Becoming eligible does not always mean enrolling in Part B right away. If you are still actively working and covered under an employer group health plan — often called an EGHP — through a company with 20 or more employees, that employer plan is generally primary. It pays its share first. Medicare Part B would pay second.
Two separate legal standards apply here. The 20-or-more employee threshold determines whether Medicare is primary or secondary — that is the Medicare Secondary Payer rule. Whether delayed Part B enrollment avoids a late penalty is a different question under a separate rule — one that generally requires active employment and active EGHP coverage. These are related but distinct standards. Confirm your specific situation with Social Security or Medicare before relying on delayed enrollment.
For more on coverage decisions while working past 65, see Working Past Age 65.
The Medigap Open Enrollment Window
Medicare Supplement Insurance — also called Medigap — is private coverage sold to help pay some of the costs that Original Medicare does not cover. When a person first enrolls in Medicare Part B at age 65 or older, a one-time, six-month Medigap open enrollment period begins automatically.
During this window, a Medigap insurer cannot deny an application or charge a higher premium based on health history. Once this window closes, insurers in most states are generally permitted to use medical underwriting. Health history can then affect whether a person qualifies and what coverage costs.
Why Part B Enrollment Timing Matters
The Medigap open enrollment window is tied to when Part B begins — not to when Medicare becomes the primary payer.
Enrolling in Part B while an employer group plan is still active and primary starts the six-month Medigap window immediately. By the time employer coverage ends and Medicare becomes the main coverage, that window may already be closed or nearly gone. Medical underwriting would then apply at the exact moment Medigap becomes most valuable.
Waiting to enroll in Part B until employer coverage actually ends aligns the Medigap open enrollment window with the transition — when Medicare is primary and Medigap has real, day-to-day value.
Planning For The Transition
When employer coverage ends, a Special Enrollment Period generally allows Part B enrollment without a late penalty. That window is typically eight months from the date active employment or employer coverage ends, whichever comes first. Enrolling in Part B during that period starts the six-month Medigap open enrollment window.
Plan carefully. Confirm the employer meets the size threshold. Verify creditable coverage status directly with Medicare or Social Security. Understand the enrollment timeline before coverage changes. The Part B start date chosen can have a lasting effect on future Medigap options.
Official Sources for Making Coverage Decisions
- Medicare.gov or call 1-800-MEDICARE (1-800-633-4227) — Official federal resource for plan comparison and enrollment
- ShipHelp.org — Find free, unbiased local Medicare counseling.
- SSA.gov or call 1-800-772-1213 — Medicare enrollment for most beneficiaries
Important Considerations
We do not offer every plan available in your area. Currently we represent 5 organizations which offer 55 products in your area. Organization and product counts are based on the Gainesville, FL area. Actual plans available may vary based on your ZIP code.
This article is provided for educational purposes only and does not recommend any specific plan or carrier. CHL Insurance Solutions, LLC is a private, licensed insurance agency (FL Lic: L131407; GA Lic: 241106 — Verify →). Not affiliated with or endorsed by the US government or the federal Medicare program.
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