Posted on June 13, 2026 by Steve Shorr — No Comments ↓

How to Apply for Medicare Part B During the General Enrollment Period (GEP)

If you missed your Medicare Part B enrollment window, the General Enrollment Period may let you enroll from January 1 through March 31. Before using the GEP, check whether a Special Enrollment Period applies.

If you need Medicare Part B and missed your Initial Enrollment Period, you may need the Medicare Part B General Enrollment Period (GEP). Medicare says the GEP runs from January 1 through March 31, and coverage starts the month after you sign up. Medicare.gov — GEP coverage start rules

Before applying through the GEP, check whether you qualify for a Medicare Part B Special Enrollment Period (SEP). Medicare lists several SEP situations, including job-based coverage, loss of Medicaid/Medi-Cal, a declared disaster or emergency, bad information from an employer or plan, release from incarceration, volunteer service outside the United States, TRICARE, and other exceptional conditions. Medicare.gov — Special Enrollment Period situations

Not sure whether you should use the GEP or SEP?

Email Steve at [email protected] before submitting your application. Using the wrong enrollment period can create delays, gaps in coverage, or a Medicare Part B Late Enrollment Penalty.

Step 1: Make Sure the GEP Is Really the Right Enrollment Period

The General Enrollment Period is generally for people who missed their first chance to enroll in Medicare Part B and do not qualify for a Special Enrollment Period. Medicare says that if you miss your SEP, you may have to wait for the next GEP and may have to pay a late enrollment penalty. Medicare.gov — SEP and GEP rules

You may need the GEP if:

You already have Medicare Part A but not Medicare Part B.
You missed your Initial Enrollment Period.
You delayed Part B and no Special Enrollment Period applies.
You are outside the 8-month SEP after losing qualifying job-based employer coverage. Medicare says the job-based coverage SEP generally ends 8 months after employment or group health plan coverage ends, whichever happens first. Medicare.gov — 8-month job-based SEP

Step 2: Check These SEP Situations Before Using the GEP

Do not assume the GEP is your only option. Medicare lists these Special Enrollment Period situations on its SEP page: Medicare.gov — full SEP list

Job-based coverage: You have or had health insurance through your job, your spouse’s job, or in some disability situations a family member’s job. Medicare.gov — job-based SEP
Medi-Cal / Medicaid loss: You lost Medicaid coverage on or after January 1, 2023. In California, Medicaid is called Medi-Cal. Medicare.gov — Medicaid loss SEP
Natural disaster or emergency: You missed a sign-up chance because you, your authorized representative, legal guardian, or caregiver were affected by a declared disaster or emergency. Medicare.gov — disaster/emergency SEP
Bad information: You missed a sign-up chance because your employer or health plan gave inaccurate or misleading information. Medicare.gov — bad information SEP
Release from incarceration: You were released from custody and missed a chance to sign up while incarcerated. Medicare.gov — release from incarceration SEP
Volunteer service outside the United States: You volunteered in a foreign country and had qualifying coverage outside the United States. Medicare.gov — foreign volunteer SEP
TRICARE: Medicare lists a special timing rule for people with TRICARE.
Other exceptional conditions: Medicare says an SEP may be available under other exceptional conditions. Medicare.gov — exceptional conditions SEP

Medicare also says some situations do not qualify for a Part B SEP, including the end of COBRA or Cal-COBRA, the end of retiree coverage, missing the 8-month window after job-based coverage ended, losing Marketplace coverage, or having End-Stage Renal Disease (ESRD). Medicare.gov — situations that do not qualify for SEP

Step 3: Can You Apply Online?

For many people signing up for Medicare for the first time, Medicare’s Ready to Sign Up for Part A & Part B page says applying online at Social Security is the easiest and fastest way to sign up. Medicare.gov — apply online for Medicare

Social Security’s Sign up for Part B only page says you can apply online when you are ending an employer group health plan during a Special Enrollment Period. SSA — Part B-only online application

If you already have Medicare Part A and are adding Part B during the GEP, Medicare says you can go to SSA.gov to apply for Part B online, and you can also submit CMS-40B by fax or mail. Medicare.gov — GEP online and CMS-40B options

Step 4: Use the Correct Part B Form If You Already Have Part A

If you already have Medicare Part A and want to add Part B, use Form CMS-40B, Request for Enrollment in Medicare Part B. CMS says CMS-40B is for people who already have Medicare Part A and want to sign up for Part B. CMS — CMS-40B instructions

The current CMS-40B PDF says the form can be used during your Initial Enrollment Period, during the General Enrollment Period from January 1 through March 31, or if you are eligible for a Special Enrollment Period. CMS — CMS-40B PDF

If you do not already have Part A, CMS says not to use CMS-40B. Instead, use the Medicare/Social Security online Medicare application process for first-time Medicare enrollment. Medicare.gov — apply for Part A and/or Part B

Step 5: Submit the Application and Keep Proof

If you use CMS-40B, CMS says you can submit the signed form by mail, fax, or by visiting a local Social Security office. CMS — submit CMS-40B

Keep copies of the application, fax confirmation, mailing receipt, delivery confirmation, and any letters from Social Security or Medicare. If there is later a question about when you applied, these records may help you show what happened and when.

Step 6: Watch for Your Effective Date and First Bill

Medicare says GEP coverage starts the month after you sign up. Review your Medicare notice carefully when you receive it. Medicare.gov — GEP coverage start

If Medicare later bills you for several months at once, see our page: Why Is Medicare Billing Me for 3 or 4 Months at Once?

What About COBRA or Cal-COBRA?

COBRA and Cal-COBRA can be useful continuation coverage, but Medicare says COBRA is not considered group health plan coverage for the job-based Part B SEP. Medicare also says getting COBRA does not change when the SEP ends. Medicare.gov — COBRA and Part B SEP

This is why someone leaving active employer coverage should review Medicare timing before relying on COBRA or Cal-COBRA as a bridge.

What About the Part B Late Enrollment Penalty?

If you delayed Part B and did not have a valid enrollment reason, Medicare may charge a Medicare Part B Late Enrollment Penalty. Medicare says if you miss your Initial Enrollment Period, you may have to pay a monthly late enrollment penalty for as long as you have Part B coverage. Medicare.gov — late enrollment warning

Frequently Asked Questions

Can I apply for Part B online during the GEP?
Medicare says that if you already have Part A, you can go to SSA.gov to sign up for Part B, and you can also send completed forms to Social Security by fax or mail. Start with Medicare’s GEP sign-up instructions and Social Security’s Part B-only page.

What form do I use if I already have Part A and want Part B?
Use CMS-40B. CMS says this form is for people who already have Medicare Part A and want to sign up for Part B.

What if I lost employer coverage?
Review Employer Coverage vs Medicare and the Medicare Part B SEP page before using the GEP. Medicare says the job-based SEP generally ends 8 months after employment or group health plan coverage ends, whichever happens first. Medicare.gov — 8-month SEP rule

What if I have COBRA or Cal-COBRA?
Review COBRA and Cal-COBRA. Medicare says COBRA does not extend the job-based Part B SEP. Medicare.gov — COBRA and SEP

What if I lost Medi-Cal?
In California, Medicaid is called Medi-Cal. Medicare lists loss of Medicaid coverage on or after January 1, 2023 as a Special Enrollment Period situation. If your issue involves Medi-Cal and Medicare together, you may also want to review Dual SNP Medi-Cal and Medicare and Medi-Cal Share of Cost. Medicare.gov — Medicaid loss SEP

Will I have a late enrollment penalty?
Maybe. It depends on when you first became eligible for Part B and whether you had a valid reason to delay. Start with our Medicare Part B Late Enrollment Penalty page.