Medicare Enrollment Periods Explained
There are several enrollment windows for different parts of Medicare. Missing a deadline can cost you — higher premiums, limited plan choices, or both.
Medigap Open Enrollment Period
This is the most important window. During this period, insurers must sell you any Medigap plan they offer, regardless of your health. They cannot charge you more because of pre-existing conditions.
Initial Enrollment Period (IEP)
This is when you sign up for Medicare Part A and Part B. Your Medigap Open Enrollment doesn't start until you're enrolled in Part B, so don't delay Part B enrollment.
Special Enrollment Period (SEP)
If you delayed Part B because you had employer coverage, you may get a Special Enrollment Period when that coverage ends. Some states also offer guaranteed-issue rights for Medigap during certain SEPs.
General Enrollment Period (GEP)
If you missed your IEP and don't qualify for a SEP, you can sign up during the GEP. Coverage starts July 1. There may be a late enrollment penalty for Part B.
Medicare Advantage Open Enrollment
This applies to Medicare Advantage and Part D drug plans, not Medigap. If you're switching from Advantage back to Original Medicare + Medigap, different rules apply and you may face medical underwriting.
The key takeaway
Your Medigap Open Enrollment Period is the most important window. It's the only time you have guaranteed-issue rights — meaning no insurer can deny you or charge extra because of your health. Once it closes, buying a Medigap plan becomes harder and potentially more expensive.