Yes, you can be denied Medicare Supplement Insurance, but it depends on when you apply. During your six-month Medigap Open Enrollment Period, which begins when you first enroll in Medicare Part B at age 65 or older, insurance companies cannot deny you coverage or charge higher premiums based on your health status. This is your guaranteed issue right. Outside of this period, insurers can deny coverage based on your health through medical underwriting. They may also deny coverage for preexisting conditions, which are health problems you had during the six months before your policy starts. However, certain life events trigger guaranteed issue rights that allow you to buy Medigap without medical underwriting, such as losing employer coverage or moving out of a Medicare Advantage plan’s service area. The key is understanding these enrollment periods and your rights to ensure you get the supplemental coverage you need.