Medicare Supplement vs. Medicare Advantage: The Switching Rules Most People Don’t Hear About

One of the first big decisions at 65 is how you’ll get your Medicare coverage: Original Medicare with a Medicare Supplement (Medigap) policy, or a Medicare Advantage plan. What many people don’t hear is that switching later isn’t equally easy in both directions. Here’s a plain-language look at the rules, with notes for Texans.

Two different ways to get your Medicare coverage

Path	How it generally works
Original Medicare + Medicare Supplement (Medigap)	Part A (hospital) and Part B (medical) come from the federal program. A Medigap policy from a private insurer can help pay some of the costs Original Medicare doesn’t, like deductibles and coinsurance. Drug coverage is usually a separate Part D plan. Medigap policies only work with Original Medicare.
Medicare Advantage (Part C)	A private plan approved by Medicare that provides your Part A and Part B benefits. Many plans include drug coverage. Plans set their own networks, copays, and out-of-pocket limits, and those can change each year.

Each path has trade-offs in cost, networks, and how you pay when you get care. Which one fits depends on your health, budget, doctors, and travel plans. That’s a personal decision, and this article doesn’t recommend one over the other. It focuses on something that gets overlooked: the rules for changing your mind later.

Why switching isn’t the same in both directions

Every year from October 15 to December 7, you can switch from Original Medicare to Medicare Advantage, or from Medicare Advantage back to Original Medicare. If you’re in a Medicare Advantage plan, there’s also a January 1 to March 31 window to switch plans or return to Original Medicare.

Here’s the part people miss: those annual enrollment periods don’t apply to Medicare Supplement policies. You can return to Original Medicare during the fall window, but outside of certain protected situations, a Medigap insurer is generally allowed to ask health questions (medical underwriting). That means it may charge more or turn down an application, depending on your health.

So the question isn’t only “Which fits me today?” It’s also “If my health changes, what options would I still have?”

Your one-time Medigap Open Enrollment Period

Under federal law, you get a 6-month Medigap Open Enrollment Period. It starts the first month you have Medicare Part B and you’re 65 or older. During this time:

• An insurance company can’t refuse to sell you any Medigap policy it offers.
• It can’t use medical underwriting or charge you more because of health problems.
• Your coverage can start right away, although a waiting period of up to 6 months for a pre-existing condition may apply in some cases (often shortened or avoided if you had other qualifying coverage beforehand).

This window happens once. It doesn’t repeat every year the way the fall Medicare Open Enrollment does. The Texas Department of Insurance (TDI) also notes that you can use your open enrollment rights more than once during the six months, for example if you change your mind about a policy you bought.

Guaranteed-issue rights: protected chances to buy later

Outside the open enrollment window, there are specific situations where an insurer must sell you certain Medigap policies, must cover your pre-existing conditions, and can’t charge more because of your health. These are called guaranteed-issue rights (or “Medigap protections”). The most common federal situations include:

• Your Medicare Advantage plan leaves Medicare, stops serving your area, or you move out of its service area, and you return to Original Medicare.
• You have Original Medicare plus employer group coverage that pays after Medicare (including retiree, COBRA, or union coverage), and that coverage is ending.
• Your Medigap insurer goes bankrupt, or your policy ends through no fault of your own.
• You leave a Medicare Advantage plan or drop a Medigap policy because the company didn’t follow the rules or misled you.
• You have a Medicare SELECT policy and move out of its service area.

In most of these situations, the policies you have a right to buy are limited to certain plan letters (for people new to Medicare on or after January 1, 2020, generally Plans A, B, D, G, K, or L; for people eligible for Medicare before 2020, Plans A, B, C, F, K, or L). The timing is tight: generally no more than 63 days after your coverage ends, and in some cases you can apply up to 60 days before.

Keep your paperwork. Save letters, notices, emails, or claim denials showing your coverage ended, along with the postmarked envelope. You may need to include copies with your Medigap application to prove you have a guaranteed-issue right.

Trial rights: a 12-month “test drive”

Federal law also gives two one-time “trial rights” for people trying Medicare Advantage:

If you…	You generally have the right to buy…
Joined a Medicare Advantage plan when you were first eligible for Medicare at 65, and within the first year you decide to switch to Original Medicare	Any Medigap policy sold in your state
Dropped a Medigap policy to join a Medicare Advantage plan for the first time, have been in the plan less than a year, and want to go back	The Medigap policy you had before, if the same insurer still sells it (otherwise, certain other plan letters)

For both, you can apply as early as 60 days before your Medicare Advantage coverage ends and no more than 63 days after. Medicare notes these rights may last longer in some circumstances, so check with your state insurance department.

Separately, if you joined a Medicare Advantage plan during your Initial Enrollment Period, Medicare lets you change to another Medicare Advantage plan or go back to Original Medicare within the first 3 months you have Part A and Part B.

Notes for Texans (and anyone who may move)

• State rules differ. Some states add their own Medigap protections, such as extra or annual switching windows. Texas’s rules are described in the Texas Department of Insurance’s Medicare supplement guide. If you live in another state or plan to move, check that state’s rules.
• Texas guaranteed-issue timing. TDI describes the guaranteed-issue right as good for 63 days from the date coverage ends or the date of notice that it will end, whichever is later.
• Under 65 with a disability. In Texas, people under 65 who have Medicare because of a disability have a six-month open enrollment period that applies to Plan A only, and another open enrollment period during the first six months after turning 65.
• 30-day free look. Texas allows you to return a Medicare supplement policy within 30 days for a refund. TDI notes the free look doesn’t apply to Medicare Advantage.
• Free help. TDI’s Help Line is 800-252-3439, and Texas HICAP (the state’s free Medicare counseling program) is 800-252-9240.

Questions to think through before you decide

• Am I still inside my 6-month Medigap Open Enrollment Period?
• Are my doctors and hospitals in the networks I’m considering?
• Do I travel or spend part of the year in another state?
• If my health changed in a few years, would I want the option of a Medigap policy, and would I likely qualify?
• Do I have retiree coverage that could be affected by the choice I make? (Medicare advises checking before you join a plan, so you don’t risk losing it.)
• Do I know my trial-right deadline, if I’m trying Medicare Advantage for the first time?

A note on this article

This is general education about federal and Texas rules as published on the official sites listed below. It isn’t advice about any specific plan, insurer, or benefit, and rules can change. For help with your own situation, Medicare (1-800-MEDICARE), Texas HICAP, and TDI are all good places to start.

If you live in Texas or one of the other states where I’m licensed, and you’d like to talk through how Medicare decisions fit with the rest of your retirement and family planning, I’m happy to answer questions plainly, with no pressure. You’re welcome to book a conversation This is a solicitation for insurance. or call me at 346-258-7080. For free, unbiased one-on-one Medicare counseling, you can also call the Texas Health Information, Counseling and Advocacy Program (HICAP) at 800-252-9240.

Chris Gavrel, independent licensed insurance agent

This article is for general educational purposes only and is not legal, tax, or financial advice. Medicare rules, enrollment periods, and dollar amounts change, and some rules vary by state. Confirm current details with Medicare.gov, Social Security, or your state’s insurance department before making a decision.

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