What Is the Medigap Open Enrollment Period?
The Medicare Supplement Open Enrollment Period (OEP) is a federally protected, one-time, 6-month window that begins on the first day of the month in which you are both age 65 or older and enrolled in Medicare Part B. During this period, insurance companies are legally required to sell you any Medigap plan they offer — no health questionnaires, no medical exams, and no risk of denial.
This is not the same as the annual Medicare Open Enrollment (Oct 15–Dec 7), which covers Medicare Advantage and Part D changes. The Medigap OEP is personal to you, triggered by your own Part B enrollment date. It happens once, and it is the single most important enrollment window in your Medicare journey.
Example: If your 65th birthday is in June and you enroll in Part B starting June 1, your Medigap OEP runs from June 1 through November 30.
Delayed Part B Enrollment?
Guaranteed Issue Rights: What They Mean for You
Guaranteed issue is the cornerstone protection of the Medigap OEP. When you have guaranteed issue rights, insurers must:
- Accept your application regardless of your health history
- Cover pre-existing conditions without any waiting period
- Charge you the standard rate — they cannot price you higher due to health status
This applies to Medigap Plans A, B, C, D, F, G, K, and L (availability varies by state). Plan F and Plan C are only available to those who became eligible for Medicare before January 1, 2020.
During Medigap OEP
- Guaranteed acceptance
- No health questions
- Pre-existing conditions covered
- Standard pricing for all
After Medigap OEP
- Can be denied coverage
- Medical underwriting required
- Pre-existing conditions may be excluded
- Higher premiums based on health
Special Guaranteed Issue Rights (Outside the OEP)
Even after your Medigap OEP ends, certain life events can trigger temporary guaranteed issue rights, giving you a 63-day window to enroll without underwriting. Common qualifying situations include:
| Triggering Event | Plans Available |
|---|---|
| Losing employer/union retiree coverage | Plans A, B, C, D, F, G, K, L |
| Medicare Advantage plan leaves your area | Plans A, B, C, D, F, G, K, L |
| You move out of your MA plan's service area | Plans A, B, C, D, F, G, K, L |
| MA trial right exercised within first 12 months | Plans A, B, C, D, F, G, K, L |
| Your Medigap insurer goes bankrupt or commits fraud | Plans A, B, C, D, F, G, K, L |
Medicare Savings Tip
What Happens If You Miss the Medigap Open Enrollment Period?
Missing your 6-month window doesn't permanently lock you out of Medigap — but it significantly changes the rules. Outside the OEP (and without a qualifying guaranteed issue event), insurers in most states can:
- Deny your application entirely based on health status
- Charge higher premiums due to age or pre-existing conditions
- Exclude coverage for certain conditions for a set period
Approximately 23% of Medicare beneficiaries have Medigap coverage, and delayed enrollment is one of the leading reasons many find themselves unable to qualify later on.
Applying After the OEP
State-Level Exceptions: Birthday Rules, Anniversary Rules & Year-Round Enrollment
While federal law governs the 6-month Medigap OEP, many states have enacted additional protections that can give you ongoing opportunities to shop or switch plans — even after your OEP has closed.
States with Year-Round Guaranteed Issue
A handful of states offer continuous open enrollment, meaning you can apply for or switch Medigap plans at any time without underwriting:
- New York — Year-round guaranteed issue for all Medicare-eligible residents
- Connecticut — Year-round guaranteed issue
- Massachusetts — Broad protections with its own Medigap system
- Maine — Continuous open enrollment protections
If you live in one of these states, the urgency of the initial OEP is lower, though enrolling early still often secures the lowest rates.
The Birthday Rule: A Second Chance Every Year
Many states now offer a "birthday rule" — an annual window (typically 30 to 63 days) around your birthday during which you can switch to an equal or lesser Medigap plan with a different carrier, no underwriting required. As of 2026, the following states have enacted birthday rules:
| State | Window | Benefit Switch Allowed |
|---|---|---|
| California | 60 days | Equal or lesser plan |
| Oregon | 60 days | Equal or lesser plan |
| Idaho | 63 days | Equal or lesser plan |
| Nevada | 60 days | Equal or lesser plan |
| Maryland | 30 days | Equal or lesser plan |
| Louisiana | 63 days | Equal or lesser (same issuer) |
| Illinois | 45 days | Equal or lesser (same issuer/affiliate) |
| Kentucky | 60 days | Same plan only |
| Virginia | 60 days | Same plan only |
| Wyoming | 63 days | Similar or lesser plan |
| Utah | 60 days | Similar or lesser (same issuer) |
| Delaware | 30 days | Similar or lesser plan (effective 2026) |
| Indiana | 60 days | Same plan only (effective 2026) |
Medicare Savings Tip
Important: Birthday rules allow you to switch to equal or lesser plans — not upgrade to a plan with richer benefits. You typically cannot move from Plan G to Plan F using a birthday rule.
Don't Confuse These Two Enrollment Periods
One of the most common Medicare mistakes is confusing the annual Medicare Open Enrollment Period (Oct 15 – Dec 7) with the Medigap OEP. Here's the key distinction:
Annual Medicare OEP (Oct 15–Dec 7)
- Applies to ALL Medicare enrollees
- Change Medicare Advantage plans
- Enroll in or change Part D
- Does NOT apply to Medigap
Medigap OEP (Your Personal Window)
- One-time, personal 6-month window
- Applies to Medigap only
- Triggered by your Part B start date
- Strongest Medigap protections available
The October 15–December 7 window is for Medicare Advantage and Part D changes. It has no impact on Medigap enrollment rules or guaranteed issue protections. Your Medigap OEP is entirely separate and based on your own enrollment timeline.
Turning-65 Enrollment Checklist
Use this timeline to stay on track when you're approaching Medicare eligibility:
| Timeframe | Action |
|---|---|
| 3 months before turning 65 | Sign up for Medicare Parts A & B (Initial Enrollment Period opens) |
| Month you turn 65 + enroll in Part B | Medigap OEP begins — 6-month clock starts |
| During your 6-month OEP | Compare Medigap plans; apply for the plan that fits your needs |
| Before OEP ends | Finalize your Medigap plan selection — guaranteed issue ends after this |
| After OEP closes | Monitor for qualifying events (job loss, MA plan changes) that trigger special rights |
| Each year (birthday rule states) | Check if you can switch to a lower-premium plan during your birthday window |
For a deeper look at which plans offer the most value, explore the best Medicare supplement plans available in 2026.
Frequently Asked Questions
When exactly does my Medigap Open Enrollment Period start?
Your Medigap OEP begins on the first day of the month in which you are both age 65 or older and enrolled in Medicare Part B. If you delayed Part B enrollment due to employer coverage, your OEP starts when your Part B coverage begins — not when you turned 65. The window lasts exactly six months from that start date.
Can I be denied Medigap coverage if I have pre-existing conditions?
During your Medigap OEP or a qualifying guaranteed issue event, no — insurers cannot deny you or charge you more due to pre-existing conditions. Outside of these protected windows, however, most states allow medical underwriting, which means an insurer can deny your application or charge you significantly higher premiums based on your health history.
What is the birthday rule and which states have it?
The birthday rule is a state-level protection that gives you an annual window — typically 30 to 63 days around your birthday — to switch to an equal or lesser Medigap plan without medical underwriting. As of 2026, states with birthday rules include California, Oregon, Idaho, Nevada, Maryland, Louisiana, Illinois, Kentucky, Virginia, Wyoming, Utah, Delaware, and Indiana. Each state has different rules about the window length and which carriers are eligible.
Is there any way to get Medigap after missing my open enrollment period?
Yes, but it is more difficult. Outside your OEP, you may still qualify through guaranteed issue rights triggered by specific events — such as losing employer coverage, your Medicare Advantage plan leaving your area, or exercising a trial right within your first 12 months on MA. You also have the option to apply with underwriting at any time, but there is no guarantee of acceptance. Residents of New York, Connecticut, Maine, and Massachusetts have year-round guaranteed issue protections.
Does the annual Medicare Open Enrollment Period (Oct 15–Dec 7) affect my Medigap plan?
No. The October 15–December 7 annual Open Enrollment Period is strictly for Medicare Advantage and Part D plan changes. It has no effect on Medigap (Medicare Supplement) plans. Your Medigap OEP is a separate, one-time window tied to your Part B enrollment date — these two periods are completely independent of each other.