What is the difference between Medicare Supplement (Medigap) and Medicare Advantage?

Almost every Medicare decision comes down to this fork. Neither one is the right answer for everybody — it depends on your doctors, your prescriptions, your travel, and your tolerance for surprise bills. Medicare Supplement (Medigap): Original Medicare plus a plan that pays most of what Medicare doesn’t. Any doctor who takes Medicare, anywhere in the country. Drug coverage bought separately. Higher monthly premium. Very predictable costs when you use care. No networks and no referrals. Medicare Advantage (Part C): A private plan that replaces Original Medicare, usually with drug coverage and extras built in. Uses a network, and your county determines what’s available. Lower or $0 monthly premium. Copays as you go, capped each year. Network matters — we check your doctors first.

When is Medicare Annual Enrollment?

Oct 15 – Dec 7. Change your Advantage or Part D plan for next year. This is the busy one — call us in September.

When is Medicare Advantage Open Enrollment?

Jan 1 – Mar 31. Already on an Advantage plan and it isn’t working? You get one switch in this window.

When is my Initial Enrollment Period for Medicare?

Your 65th. Three months before your birthday month through three months after. Late Part B enrollment carries a lifetime penalty.

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Medicare, explained in the order you actually need it.

Start with your situation. We’ll tell you what decisions are in front of you and which deadlines are real. Start with the situation you’re in. We’ll tell you what decisions are in front of you, which deadlines are real, and what happens if you wait.

Page updated November 5, 2026.

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Your situation

Which sounds like you?

I’m turning 65
Your one clean shot at a Medigap plan without health questions happens now.
Your one clean shot at a Medigap plan without health questions happens now. Here’s the seven-month window and what to do inside it.
Turning 65 guide →
I’m retiring after 65
Forms your employer signs, and a clock that starts the day you leave.
You delayed Part B while you were working. There are forms your employer has to sign, and a clock that starts the day you leave.
Leaving employer coverage →
I’m on Medicare through disability
Colorado has specific rules about supplement plans offered to you under 65.
Under 65 and on SSDI. Colorado has specific rules about what supplement plans must be offered to you — most people aren’t told this.
Medicare under 65 →
I have Medicare and Medicaid both
You may qualify for extra help with premiums and drug costs.
You may qualify for extra help with premiums and drug costs, and for plans built specifically for dual-eligible members.
Dual-eligible options →

The main decision

Supplement or Advantage

Almost every Medicare decision comes down to this fork. Neither one is the right answer for everybody — it depends on your doctors, your prescriptions, your travel, and your tolerance for surprise bills.

Medicare Supplement (Medigap)

Higher premium, very predictable costs, any doctor who takes Medicare.

Original Medicare plus a plan that pays most of what Medicare doesn’t. Any doctor who takes Medicare, anywhere in the country. Drug coverage bought separately.

Higher monthly premium
Very predictable costs when you use care
No networks and no referrals

How Medigap works in Colorado →

Medicare Advantage (Part C)

Lower or $0 premium, copays as you go, network matters — we check your doctors.

A private plan that replaces Original Medicare, usually with drug coverage and extras built in. Uses a network, and your county determines what’s available.

Lower or $0 monthly premium
Copays as you go, capped each year
Network matters — we check your doctors first

How Advantage plans work →

How to choose between them in Colorado →

Before we can talk about specific Medicare Advantage or Part D plans with you, CMS requires a signed Scope of Appointment. It takes about a minute and you can sign it once you book a call.

We do not offer every plan available in your area. Currently we represent 8 organizations which offer 51 products in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options.

Enrollment windows

Dates that matter

All enrollment periods →

Oct 15 – Dec 7
Annual Enrollment
Change your Advantage or Part D plan for next year. This is the busy one — call us in September.
What to check this fall
Jan 1 – Mar 31
Advantage Open Enrollment
Already on an Advantage plan and it isn’t working? You get one switch in this window.
Your 65th
Initial Enrollment
Three months before your birthday month through three months after. Late Part B enrollment carries a lifetime penalty.

Who you’ll talk to

Four licensed advisors. No call center.

Tina, Lexi, Evan, and Kara are each licensed for Medicare and for individual & family plans, and all of them work every plan Grove carries. Book with whoever is free — that person will know both sides of your situation.

Meet the team

“The advisors at Grove are excellent. They are knowledgeable and very thorough, and understood how to match my needs with the best product. They are responsive and efficient and really made me feel like I’m in good hands. I highly recommend!”

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Still fuzzy? Call us.

There’s no charge, no obligation, and no script. If we’re not the right help, we’ll tell you who is — including 1-800-MEDICARE.

Talk with Tina, Lexi, Evan, or Kara

5.0 on Google 12 reviews

Never a fee for our services
Phone or video
Licensed in Colorado

(970) 840-1250 Book a 60-minute call

Mon–Fri, 9am–5pm MT · TTY 711

Medicare, explained in the order you actually need it.

Free 60-minute review

Which sounds like you?

I’m turning 65

I’m retiring after 65

I’m on Medicare through disability

I have Medicare and Medicaid both

Supplement or Advantage

Medicare Supplement (Medigap)

Medicare Advantage (Part C)

Dates that matter

Annual Enrollment

Advantage Open Enrollment

Initial Enrollment

Four licensed advisors. No call center.

What a client said

More on Medicare

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