Medicare 2026

Signing Up for Part B When Job Coverage Ends: How Forms CMS-40B and CMS-L564 Work

If you delayed Medicare Part B because you were still working and covered by a group health plan, there is a specific path to pick up Part B when that job coverage winds down. It involves a Special Enrollment Period and, usually, two short forms: CMS-40B (your application) and CMS-L564 (a short questionnaire your employer fills out). Here is a plain-English walk-through so you can plan ahead and avoid a gap in coverage.

Who this path is for

This Special Enrollment Period (SEP) is for people who kept working past age 65 (or past their Medicare eligibility date) and stayed on a group health plan based on their own or a spouse's current employment. When that employment or the coverage ends, you have 8 months to sign up for Part B without a late-enrollment penalty.

A few important limits:

• You must have had group health plan coverage based on current employment (or Part B itself) for every month since you first became eligible for Part B.
• Retiree coverage and COBRA do not count as "current employment" coverage for this purpose, even if you still have them.
• This SEP does not apply if you qualify for Medicare because of End-Stage Renal Disease, and it does not apply if you are still inside your Initial Enrollment Period.

Also worth knowing: if you skip this SEP when you have it, federal rules generally do not grant another one — unless your job-based coverage was restored before the period ended.

The two forms

Form CMS-40B — Application for Enrollment in Part B. This is your request to enroll. You complete it and submit it to Social Security.

Form CMS-L564 — Request for Employment Information (revised 03/2025). This form has two sections:

• Section A — you fill out your basic information.
• Section B — your employer (or your spouse's employer, if the coverage is through them) confirms whether and when your group health coverage started and ended, and the dates you worked there.

If the employer is unresponsive or no longer in business, Medicare.gov's guidance is to complete Section B as fully as you can without signing it, and submit other documentation of your job-based coverage — for example, pay stubs showing health insurance deductions, W-2s, insurance cards, or statements from the health plan.

How to submit

You have two options: 1. Apply online through Social Security. This is often the fastest route. 2. Mail or fax the completed CMS-40B and CMS-L564 to your local Social Security office.

Either way, Social Security — not CMS directly — processes Part B enrollments.

When Part B will start

There are two rules to understand here, and they fit together.

Under federal regulations and the current Form CMS-40B (07/2025), if you enroll while still covered by the job-based plan, or during the first full month after it ends, you may choose for Part B to start on the first day of the month you enroll or on the first day of any of the next three months. That flexibility lets you line Part B up with the day your employer coverage actually ends.

If you enroll later in the 8-month window, Part B starts the first day of the month after you enroll — no month-picking.

Medicare.gov's shorter plain-language version says coverage starts the month after Social Security processes your completed form, and advises checking when your employer coverage ends and signing up about a month earlier so you do not have a gap.

Practical tip: build in time for processing and for any back-and-forth about the CMS-L564. Starting the paperwork before your last day of coverage is almost always easier than starting it after.

After Part B begins: your other decisions

Once Part B is active, you have real choices about how to receive your Medicare benefits. Two main paths exist, and neither is "better" — they are different trade-offs.

• Original Medicare (Parts A and B), often paired with a stand-alone Part D drug plan and, for some people, a Medigap policy. You can generally see any provider who accepts Medicare. Medigap can help with cost-sharing; availability and pricing of Medigap vary and are worth checking carefully.
• A Medicare Advantage plan (Part C), which bundles Part A, Part B, and usually Part D through a private plan. These plans often use provider networks and may include extras, but rules, networks, and costs vary plan by plan.

Compare based on your doctors, your prescriptions, your travel patterns, and your tolerance for network rules versus predictable supplemental coverage.

A few 2027 numbers to keep in mind

• The Part D out-of-pocket cap is $2,400 in 2027 (it is $2,100 in 2026).
• The maximum Part D deductible any plan may charge in 2027 is $700.
• The Part D base beneficiary premium for 2027 is $41.33 (used to calculate the late-enrollment penalty; actual plan premiums vary).
• Annual Enrollment runs October 15 – December 7, 2026, with choices effective January 1, 2027.
• Social Security announced a 3.6% COLA for benefits starting January 2027.

The 2027 Part B standard premium and deductible, and the 2027 IRMAA income brackets, had not been announced at the time of writing. CMS typically releases those figures in the fall.

If you have Medicaid or Extra Help

Since 2025, people enrolled in Medicaid or the Part D Extra Help program have a monthly Special Enrollment Period to move to Original Medicare with a stand-alone Part D plan, or to switch stand-alone Part D plans. Full-benefit dual-eligible individuals can also join an integrated D-SNP in any month.

Where can you get help with Medicare questions?

For the official forms, enrollment instructions, and up-to-date program figures, visit Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048, 24 hours a day, 7 days a week.