Medicare Supplement FAQs

What is Medicare Supplement Insurance?

Medicare Supplement Insurance is a private health insurance policy designed to help pay some or all of the costs that are not covered by Medicare Parts A and B.

Who is eligible for Medicare Supplement Insurance?

Anyone who is covered under both Medicare parts A and B is eligible for Medigap Coverage.

When can I apply for Medicare Supplement Insurance?

You can apply for Medicare Supplement Insurance during open enrollment. Open enrollment includes a six-month period from the date you enrolled in Medicare Part B if age 65 or older, or up to six-month after you turn 65 if you were eligible for Part B benefits before age 65. If you become eligible for Medicare Part B benefits before age 65 because of disability or ESRD (permanent kidney failure), you are guaranteed the Medicare Supplement policy of your choice during the first six months you are age 65 and enrolled in Part B.

Does Medicare Supplement coverage include prescription drug benefits?

No, Medicare Supplement is designed to fill in the “gaps” with Medicare Plans such as Part A (which covers hospital and skilled nursing facility care) and Part B (which covers doctor bills and other medical expenses).

For prescription drug coverage, you can select a separate Medicare Part D Prescription Drug Plan. In Illinois, there are 2 major companies that offer Medicare Prescription drug coverage, Humana and BlueCross BlueShield of Illinois. For more information on Medicare Part D Plans, click on the links below:

• Humana Medicare Prescription Drug Plans
• BlueCross BlueShield of Illinois Medicare Prescription Drug Plans

Can I enroll if I do not have Medicare Parts A or B?

No, you must be entitled to Medicare Part A and/or enrolled in Medicare Part B to be eligible for a Medicare supplement plan.

To learn how to get Medicare Part A and/or Part B, please call Medicare at 1-800-MEDICARE (1-800-633-4227), 24 hours a day/7 days a week. For the hearing or speech impaired, please call 1-877-486-2048.

You may also contact your State Medicaid Office or the Social Security Administration at 1-800-772-1213, Monday-Friday, 7 a.m.-7 p.m. CST. For the hearing or speech impaired, please call 1-800-325-0778.

Does Everyone Need a Medicare Supplement Policy?

Not everyone needs a Medicare supplement policy. If you have certain other types of health coverage, the gaps in your Medicare coverage may already be covered. You probably don’t need Medicare supplement insurance if

• you belong to a Medicare Advantage plan
• Medicaid or the Qualified Medicare Beneficiary (QMB) Program pays your Medicare premiums and other out-of-pocket costs.
• You are covered under an employer group health plan

What if I (or my spouse) plan to work after age 65 and continue receiving group health care benefits?

Check with your group plan administrator. You may be able to choose either your group plan or Medicare plus Medicare Supplement coverage. If you stay with your group health care plan, a Special Enrollment Period lets you delay purchasing Part B until you need it.

Will I need to switch doctors if I enroll in a Medicare Supplement plan?

No, you may continue to see your own doctor. Medicare Supplement plans are convenient and flexible, giving you freedom of choice.

Can I see a specialist whenever I want?

Yes. Just remember that your out-of-pocket costs will be less if you choose a physician who accepts Medicare assignment.

What percent of Illinois doctors accept Medicare assignment?

About 9 out of 10. In the Medicare enrollment data CMS publishes for Care Compare (Doctors and Clinicians national file, updated August 2026), 90.5% of the 69,027 Medicare-enrolled clinicians in Illinois are listed as accepting Medicare assignment. Among physicians (MDs and DOs) the rate is 93.9%, among primary care doctors it is 94.4%, and among surgeons it is 96.4%. The rest are listed as “may accept,” meaning they decide claim by claim. Doctors who have opted out of Medicare entirely are not in this data.

Why it matters: a doctor who accepts assignment takes the Medicare-approved amount as full payment, so you owe only your normal share. A doctor who does not can charge up to 15% above the Medicare-approved amount (an “excess charge”). Medicare Supplement Plan G covers that excess charge. Plan N does not, and Plan N also has copays of up to $20 for office visits and up to $50 for ER visits that do not lead to admission. If you stay with doctors who accept assignment, Plan N can save money on premiums. You can check any doctor at medicare.gov/care-compare.

Source: CMS Doctors and Clinicians national downloadable file, each clinician counted once.