Medicare Supplement Plan Open Enrollment
Medicare Supplement Open Enrollment is a six-month window that begins the first month you are 65 or older and enrolled in Medicare Part B. During this period, you can buy any Medigap policy sold in your state without medical underwriting. Insurers cannot deny you coverage or charge you more because of preexisting health conditions. This is the strongest protection most people will ever have when buying a Medicare supplement plan.
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If you miss this window, you can still apply for Medigap later, but insurers may ask about your health history, charge higher premiums, or decline coverage altogether. Understanding the timing and rules now can save you from gaps or unexpected costs down the road.
When Does Medicare Supplement Open Enrollment Start
The six-month period is tied to your Medicare Part B effective date, not your birthday or the calendar year. It begins on the first day of the month you turn 65 and enroll in Part B. For most people, that is also the month they become eligible for Medicare, but if you delay Part B, the clock does not start until you sign up.
- Month one of the window: the first month you are both 65 or older and enrolled in Part B.
- The window runs for six full months, regardless of when it starts.
- If you are eligible for Part B before age 65 because of a disability, your open enrollment starts when Part B begins.
Guaranteed-Issue Rights During Open Enrollment
Guaranteed issue means an insurance company must sell you a Medigap policy if you ask during the open enrollment period. They cannot:
- Require a medical exam.
- Ask about your health history on the application.
- Charge you a higher premium based on health status.
- Decline coverage or place a waiting period on preexisting conditions.
These rights are powerful, and they apply to every Medigap plan the company offers in your state. You do not have to explain why you want coverage, and insurers cannot push you toward a specific plan type during this window.
What Medicare Supplement Plans Cover
Medicare Supplement plans, also called Medigap, help pay for out-of-pocket costs Original Medicare does not cover. The standard plans are labeled A through N, and each offers a different combination of benefits. All standardized plans with the same letter cover the same core benefits, though prices and extra perks can vary by insurer.
| Benefit | Covered by All Medigap Plans | Notes |
|---|---|---|
| Part A coinsurance and hospital costs | Yes | Up to an additional 365 days after Medicare benefits end |
| Part B coinsurance or copayment | Yes | Typically 20 percent of the Medicare-approved amount |
| Blood (first 3 pints) | Yes | Copay may apply in some plans |
| Skilled nursing facility coinsurance | Yes | Coverage limited to a set number of days |
| Part A deductible | Plan B and higher | Not included in Plan A |
| Part B deductible | Plan C and F only (no longer sold to new enrollees after 2020) | New Medicare enrollees cannot buy these plans |
| Foreign travel emergency | Plans C, D, F, G, M, N | Coverage is limited and subject to a deductible |
How to Choose a Medigap Plan
During open enrollment, focus on two things: the coverage that matches your needs and the price structure that fits your budget. Medigap premiums vary widely by plan, company, and location, even when the core benefits are identical.
- Standardized coverage. Pick the letter first, then compare prices among insurers. A Plan G from one company pays the same as a Plan G from another, but the premium can differ by hundreds of dollars a year.
- Premium types. Insurers use community-rated, issue-age-rated, or attained-age-rated pricing. Community-rated premiums do not change as you get older, while attained-age-rated premiums increase with age.
- Additional benefits. Some plans offer extra perks like vision or hearing benefits, but these are not standardized and can change from year to year.
What Happens After Medicare Supplement Open Enrollment
Once the six-month window closes, guaranteed-issue rights end. If you apply for Medigap later, the insurer can review your health history, charge a higher premium based on your conditions, or decline to sell you a policy. Some exceptions exist, including certain life events like moving out of your plan's service area or losing other creditable coverage, but those protections are narrower than open enrollment.
If you are still working past 65 and have group coverage from an employer with 20 or more employees, you may be able to delay Part B without penalty, which also delays the start of your open enrollment. Check how your current coverage and Medicare coordinate before you decide, because the timing of Part B enrollment directly affects both your Medicare rights and your Medigap window.