Original Medicare covers hospital visits and outpatient treatment, but it leaves patients paying deductibles, copayments, and coinsurance with no out-of-pocket cap. Medigap, also called Medicare Supplement Insurance, is private coverage that pairs with Original Medicare and significantly reduces those out-of-pocket costs.
The best time to get a Medigap plan is during your Medigap Open Enrollment Period, which occurs when you first enroll in Medicare. During this period, insurance companies are required to accept your application and cannot charge you more based on your health history. Outside of this period, it may be more challenging to get a Medigap policy.
This article walks you through when your Medigap Open Enrollment Period is, what happens if you miss it, and what to do if you want to change your Medigap plan later.
If you need personalized advice, we’re here to help. Our licensed Medicare Advisors can help you compare Medigap plans and other Medicare coverage options based on your budget and healthcare needs.
Key takeaways
The Medigap Open Enrollment Period is a one-time, six-month window. It begins on the first day of the first month when you’re 65 or older and enrolled in Medicare Part B.
You can still apply for Medigap if you miss this window, but you may be subject to medical underwriting, and insurers may deny your application or charge you more based on your health history.
Medigap plans and rules differ by state, so ask one of our Chapter Advisors for details.
What’s the Medigap Open Enrollment Period, and when does it start?
The Medigap Open Enrollment Period, also called the Medicare Supplement Open Enrollment Period, is a one-time, six-month window. It starts on the first day of the first month when you’re both 65 or older and enrolled in Medicare Part B.
This is generally the best time to buy Medigap because you’re guaranteed to be accepted into any policy, regardless of your health or pre-existing conditions. During this window, Medigap insurers are not allowed to use medical underwriting, deny you coverage, or charge you higher premiums because of health conditions.
If you’re under 65 and already have Medicare because of a disability or end-stage renal disease (ESRD), you don’t automatically qualify for Medigap. Federal law doesn’t require insurers to provide Medigap to people under 65. However, you might be able to get a plan in certain states. More than 30 states require insurance companies to offer at least one Medigap plan to people under 65 who have Medicare.
Although the names are similar, Medigap Open Enrollment Period is distinct from Medicare Open Enrollment. The Medicare Open Enrollment window occurs every year, the Medigap window occurs only once and is unique to you. You can still apply for Medigap outside of your Medigap Open Enrollment Period, but you are no longer guaranteed acceptance into plans.
What happens if you miss Medigap Open Enrollment?
Medigap enrollment rules change after the Medigap Open Enrollment Period ends. In this section, we’ll explore what you can do if you miss it.
Can you get a Medigap plan after your Medigap Open Enrollment window closes?
After your Medigap Open Enrollment Period closes, you can still apply for a Medigap plan, but you don’t have the same protections. You’re no longer guaranteed coverage. Medigap insurers can now ask you questions about your health and use medical underwriting to decide whether to offer you coverage—and how much you’ll pay. If you have serious pre-existing conditions, they may deny your application or charge you more.
There are a couple of exceptions to this general rule. The Medicare website outlines specific situations in which you have guaranteed issue rights, meaning insurers must sell you a policy and can’t charge more for pre-existing conditions. For example, you have guaranteed issue rights if your current Medigap plan ends through no fault of your own.
Four states (Connecticut, Maine, Massachusetts, and New York) also have continuous guaranteed issue protections for all Medicare beneficiaries aged 65 and older, regardless of medical history.
If you have a Medicare Advantage plan, you won’t be able to get a Medigap plan as well. To be eligible for Medigap, you’d need to cancel your Medicare Advantage plan during a qualifying enrollment period and return to Original Medicare.
What if you delay enrolling in Medicare Part B?
Some people choose not to enroll in Medicare Part B when they turn 65 because they have qualifying coverage from an employer or other health insurance plan. If you delay Medicare Part B enrollment, then your Medigap Open Enrollment Period is delayed as well. Medigap eligibility starts when you enroll in Medicare Part B, whether that’s at age 65 or later.
For example, let’s say you continue working until age 72. You have good coverage from your employer, so you remain on your work-provided insurance and delay Medicare Part B.
When you retire, you lose your employer’s health insurance and want to enroll in both Medicare Part B and Medigap. You now have an eight-month Medicare Part B Special Enrollment Period to enroll in Medicare Part B without facing a penalty. After you sign up for Medicare Part B, your Medigap Open Enrollment Period starts on the first day of the month that the Part B coverage takes effect and lasts for six months.
Can you change your Medicare Supplement (Medigap) insurance plan?
You can technically enroll in or change your Medigap plan at any time. But keep in mind that if you’re outside the Medigap Open Enrollment Period or other guaranteed issue periods, you’ll run into the same issues we discussed earlier: medical underwriting and possible denial of your application based on pre-existing conditions.
However, in 18 states, there’s a short window when you can switch to a different Medigap plan without being subject to medical underwriting. This period may be between 30 and 63 days around your birthday—or when you first enrolled in Medigap—each year. In this window, Medigap insurers can’t deny you coverage. The eligibility rules and the length of the window vary by state, and you can generally only switch to a plan with equal or fewer benefits.
Because Medigap plans are standardized in most states, you get the same benefits on every plan of the same letter. So most decisions to switch are about rising premiums, dissatisfaction with your current plan’s customer service, or securing better coverage for out-of-pocket costs.
Are Medigap plans different in each state?
In most states, Medigap plans are standardized: The core benefits for the same lettered plan are the same with every insurance company. So a Medigap Plan G policy from one company will offer the same benefits as a Medigap Plan G policy with a different firm.
But there are a few distinctions from state to state. For instance, availability and eligibility rules may differ. Here are a few things that vary by state:
Plan structure and names: In Massachusetts, Minnesota, and Wisconsin, insurers don’t use the usual federal plans with letters from A to N. They have their own plans with different names—like Wisconsin’s Basic Plan or Minnesota’s Extended Basic Plan.
Plan availability: Although the federal plans are standardized, they’re not all offered in every state, and insurance companies may not offer policies for every type of plan.
Under-65 eligibility: People under 65 aren’t guaranteed eligible for Medigap under federal law, but in some states you may be able to get Medigap if you’re already on Medicare because of a disability or ESRD.
Guaranteed issue periods and switching rules: Four states have continuous guaranteed issue protections, and 18 have birthday or anniversary rules to help you switch plans without medical underwriting.
Premium rating rules and pricing factors: Some states regulate which rating (pricing) structures insurers can use to set premiums. This, and factors like local insurance rates, affect state-by-state premiums. For example, the average monthly Medigap premium in 2023 was $191 in Alaska but $267 in New York.
Get help choosing a Medicare Supplement plan
Medigap plans are a helpful way to control out-of-pocket costs, but choosing one can feel overwhelming. Even after you understand timing and eligibility, you need to detangle the different Medigap plans, the benefits they offer, and the differences in policies offered by insurance carriers in your area.
To help navigate these plans and pick the right one based on your situation, give us a call at 855-900-2427 or book a free consultation with a Chapter Medicare Advisor. We’ll help you understand the timing of Medigap enrollment, compare plans, and secure coverage that meets your needs.
FAQ
Can you switch Medigap plans after Medigap Open Enrollment ends?
Yes, but after Medigap Open Enrollment ends, you’ll generally be subject to medical underwriting and insurance companies can deny your application or charge you more for a Medigap policy based on your health history.
What’s the most common misunderstanding about the Medigap Open Enrollment Period?
People may confuse the Medigap Open Enrollment Period with Medicare Open Enrollment. The Medicare Open Enrollment window occurs every year between October 15 and December 7 and allows people to enroll in Medicare Advantage, change their Medicare Advantage plan, leave Medicare Advantage and return to Original Medicare, or enroll in or change their Part D plan. On the other hand, the Medigap Open Enrollment Period is one time only and lets people enroll in Medigap plans with guaranteed acceptance.
What happens after your Medigap Open Enrollment Period ends?
After your Medigap Open Enrollment Period ends, you lose guaranteed acceptance to a Medigap policy (outside of a handful of exceptions). You can still apply for a plan, but you could be subject to medical underwriting and may be denied coverage or charged more based on your health history.
Sources
Medicare (2026). Get ready to buy. https://www.medicare.gov/health-drug-plans/medigap/ready-to-buy
Kaiser Family Foundation (2024). Medigap May Be Elusive for Medicare Beneficiaries with Pre-Existing Conditions. https://www.kff.org/medicare/medigap-may-be-elusive-for-medicare-beneficiaries-with-pre-existing-conditions/
CBS News (2025). What is the Medigap birthday rule and how does it impact seniors? https://www.cbsnews.com/news/what-is-the-medigap-birthday-rule-and-how-does-it-impact-seniors/
Kaiser Family Foundation (2026). Medigap Premiums Leap, and Consumers Have Few Alternatives. https://kffhealthnews.org/medicare/medigap-medicare-advantage-premiums-rate-increase-few-alternatives/
Kaiser Family Foundation (2024). Key Facts About Medigap Enrollment and Premiums for Medicare Beneficiaries. https://www.kff.org/medicare/key-facts-about-medigap-enrollment-and-premiums-for-medicare-beneficiaries/
