Medigap plans, also known as Medicare Supplement Insurance, help cover costs not paid by Original Medicare, including copayments, deductibles, and coinsurance expenses. These plans are offered by private insurance companies and work exclusively alongside Original Medicare Parts A and B, not Medicare Advantage. Medigap plans offer standardized coverage identified by letters (Plans A, B, C, D, F, G, K, L, M, N), making it easier for beneficiaries to compare policies across insurers. While each lettered plan provides identical coverage benefits regardless of the insurer, premiums can differ widely based on location, provider, age, and sometimes health status. Beneficiaries must have Medicare Part A and Part B before purchasing a Medigap policy. The ideal time to enroll in a Medigap policy is during the Medigap Open Enrollment Period, which lasts six months starting the month beneficiaries turn 65 and enroll in Medicare Part B.