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How to Sign Up for Medigap: Step-by-Step Guide to Enrolling in a Medicare Supplement Plan

Reviewed by Russell Noga, Licensed Medicare Insurance Broker (all 50 states) — Last updated October 25, 2026

Key Takeaway

To sign up for Medigap, enroll in Medicare Parts A and B, pick a plan letter, compare companies and apply with the insurance company or a licensed agent. Apply during your 6-month open enrollment period so you can’t be turned down for your health.

Signing up for a Medicare Supplement plan, also called Medigap, is not like signing up for Medicare. You don’t do it through Social Security or Medicare.gov. You apply with a private insurance company, and when you apply matters as much as which plan you pick. Here is exactly how to sign up for Medigap, step by step.

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Who Can Sign Up for Medigap

How to sign up for Medigap: sign up for Medicare Parts A and B through Social Security, then buy a Medigap plan from an insurance company or agent

You can buy a Medicare Supplement plan if you have Original Medicare. Before your plan can start, you need:

✔
Medicare Part A (hospital insurance)
✔
Medicare Part B (medical insurance)
✔
To live in the state where the policy is sold
✔
To not be enrolled in a Medicare Advantage plan when your Medigap plan starts

Most people sign up when they turn 65. If you are under 65 and on Medicare because of a disability, your options depend on your state, since federal law does not require companies to sell to people under 65.

When to Sign Up for Medigap

Your situation When to apply Health questions?
Turning 65 and starting Part B Up to about 6 months before Part B starts, or during your 6-month open enrollment period No
Within 6 months of Part B start Any time in your open enrollment period No
Lost employer or other coverage Within 63 days with a guaranteed issue right No
After open enrollment, no special right Any time of year Yes, in most states

Your Medicare Supplement open enrollment period is the most important date in this process. It lasts 6 months, starts the month you are 65 or older and enrolled in Part B, and it only happens once.

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How to Sign Up for Medigap, Step by Step

The four pieces of Medicare coverage to sign up for: Part A hospital, Part B medical, Medigap and Part D drug coverage
1
Enroll in Medicare Parts A and B. Sign up through Social Security if you are not enrolled automatically.
2
Pick a plan letter. Most new enrollees choose Plan G, Plan N or High-Deductible Plan G.
3
Compare insurance companies. Benefits are the same for each plan letter, so compare price, rate history and discounts.
4
Fill out the application. Apply with the company directly or through a licensed agent, online or by phone.
5
Pay your first premium. Your coverage starts once the company approves you and receives payment.
6
Sign up for Part D. Add a separate drug plan, since Medigap does not cover prescriptions.

Choosing Your Plan Letter Before You Apply

There are 10 standardized Medicare Supplement plan letters, but most people who sign up today choose one of three. Plan G covers almost everything Original Medicare leaves you to pay except the Part B deductible. Plan N costs less each month in exchange for small copays at the doctor and emergency room. High-Deductible Plan G has the lowest premium, but you pay a yearly deductible before it starts paying.

Pick your plan letter before you compare companies. Because benefits are identical for each letter, the only real differences between companies are price, rate history, discounts and service. Comparing Plan G at one company to Plan N at another leads to a bad decision.

Good to know: Plans C and F are only available to people who were eligible for Medicare before January 1, 2020. If you are new to Medicare now, Plan G is the closest option to full coverage.

See every option side by side in our guide to Medicare Supplement plans.

What You Need Before You Apply

✔
Your red, white and blue Medicare card or your Medicare number
✔
Your Part A and Part B start dates
✔
Your bank account or card for the first premium
✔
A list of your medications and doctors, in case health questions apply
✔
Proof of prior coverage if you are using a guaranteed issue right

Having these ready can turn a long application into a 15-minute phone call with a licensed agent.

Where to Sign Up

Licensed Agent

✔Compares many companies at once
✔Helps with the application
✔No cost to you

Insurance Company

✔Apply with one company directly
✔You compare prices yourself
✔Same price as through an agent

Not Medicare.gov

✔Medicare does not sell Medigap
✔Social Security does not either
✔Only private companies do

Medicare Supplement prices are filed with your state, so you pay the same premium whether you buy through an agent or directly from the company.

Example: Signing Up When You Turn 65

Say your 65th birthday is in June and your Part B starts June 1.

March to May

✔Apply for your Medigap plan
✔Pick a June 1 start date
✔No health questions

June 1

✔Medicare and Medigap start together
✔No gap in coverage
✔Part D starts too

June to November

✔Your open enrollment window
✔Still no health questions
✔Ends November 30

Example only. How early you can apply depends on the insurance company and your state.

Mistakes to Avoid When You Sign Up

Medigap open enrollment period: apply early, no health questions for 6 months, health questions after the window closes
✔
Waiting until after your open enrollment period ends, when health questions can apply
✔
Skipping Part D, which can lead to a lifetime late enrollment penalty
✔
Comparing different plan letters instead of the same plan across companies
✔
Canceling other coverage before your new Medigap policy is approved

If you have health problems, timing matters even more. See how Medicare Supplement pre-existing conditions rules work before you apply.

The Bottom Line

Signing up for Medigap is simple once you know the order: Parts A and B first, then a plan letter, then the best company for your ZIP code. Apply during your open enrollment period, and a licensed insurance agent can handle the whole process at no cost.

Get help signing up for Medigap

Speak with a licensed insurance agent

1-888-891-0229

Keep Reading

Medigap Trial Right: how to leave Medicare Advantage within 12 months and get a Medicare Supplement plan with no health questions.

How to Sign Up for Medigap — Frequently Asked Questions

➤ How do I sign up for Medigap?

You sign up directly with a private insurance company, usually through a licensed insurance agent. Pick a plan letter, compare companies, fill out the application and pay your first premium. You cannot sign up for Medigap on Medicare.gov or through Social Security.

➤ When is the best time to sign up for Medigap?

The best time is your 6-month Medicare Supplement open enrollment period, which starts the month you are 65 or older and enrolled in Part B. During that window, companies cannot turn you down or charge more because of your health.

➤ Do I need Medicare Part A and Part B to get Medigap?

Yes. You must be enrolled in both Part A and Part B before your Medicare Supplement plan can start.

➤ Can I apply for Medigap before my Part B starts?

Many insurance companies let you apply up to about six months before your Part B start date so your plan begins the same day as Medicare. Rules vary by company and state.

➤ What do I need to sign up for a Medicare Supplement plan?

Have your Medicare card or Medicare number, your Part A and Part B start dates, your bank or card information for the first premium, and a list of your medications and doctors in case the company asks health questions.

➤ Does Medigap include prescription drug coverage?

No. Medicare Supplement plans sold today do not cover prescription drugs. Sign up for a separate Medicare Part D plan to avoid a late enrollment penalty.

➤ Can I have Medigap and Medicare Advantage at the same time?

No. A Medicare Supplement plan only works with Original Medicare. If you are in a Medicare Advantage plan, you need to leave it before your Medicare Supplement plan starts.

➤ Can a licensed agent help me sign up?

Yes. A licensed insurance agent can compare companies, help you fill out the application and make sure your start date lines up with Medicare, at no cost to you.

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Have Questions?

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