Original Medicare is Part A + Part B. Medicare Advantage is offered by private companies and is an alternative way to get Part A + Part B (and usually Part D), often with networks and different cost structures.

No — Medigap supplements Original Medicare; you generally can’t have both at the same time.

Most people start during the 7-month Initial Enrollment Period around turning 65.

If you’re working past the age of 65, the “right” Medicare step depends mainly on whether you have health coverage through current employment (yours or your spouse’s) and your employer’s size.

Start by checking with your HR/benefits office to confirm whether your plan is a group health plan based on current employment. If your employer has fewer than 20 employees, Medicare generally pays first, and you’ll usually want to enroll in Part A and Part B when first eligible.

If you have qualifying employer coverage, you may be able to delay Part B and enroll later through a Special Enrollment Period (SEP) to avoid penalties.

When you retire or your employer coverage ends, you generally have an 8-month SEP to enroll in Part B (and avoid late penalties). COBRA/retiree coverage doesn’t count as “current employment” coverage for this purpose, so timing matters.

To prevent a gap, try to enroll about a month before your employer coverage ends.

If you contribute to an HSA: once you’re enrolled in Medicare, your HSA contribution limit becomes $0, including during any retroactive Medicare coverage. Guidance commonly recommends stopping HSA contributions before applying for Medicare to avoid tax issues.

Please also note (if you’re also drawing Social Security): If you claim Social Security before full retirement age and keep working, your benefit may be temporarily reduced if earnings exceed the annual limit.