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MEDICARE PART B, WHEN DO YOU SIGN UP?

So, you’re over 65, still working (or recently stopped), and had health insurance through your job. But now that coverage is ending, you're wondering how to get Medicare Part B without paying a penalty or getting stuck without insurance.

If you didn’t sign up for Medicare Part B when you turned 65 because you had job-based insurance, that’s totally fine! Medicare gives you a Special Enrollment Period (SEP) to sign up after that coverage ends.

BUT—and this is important—you only get 8 months from the time your job-based insurance ends to sign up, or you might have to pay a monthly penalty for the rest of your life.

When employer coverage ends, whether because you are retiring or choosing to drop your work insurance, you qualify for this Enrollment Period.

Two essential forms you'll need:

  • CMS‑40B – Application for Enrollment in Medicare Part B

  • CMS‑L564 – Request for Employment Information (the "losing employer coverage" form)

📄 Form #1: CMS‑L564 (Request for Employment Information) https://www.cms.gov/cms-l564-request-employment-information

What it does:

This form tells Uncle Sam if you had work insurance since turning 65, protecting you from late enrollment penalties.

  • Section A: You complete personal details and employer info.

  • Section B: Your employer completes employment dates, coverage start/end, signs it.

If your employer can’t complete it, you may provide supporting docs: tax forms, pay stubs, insurance cards, or IRS forms showing premium deductions.

📄 Form #2: CMS‑40B (Application for Enrollment in Medicare Part B) https://www.cms.gov/medicare/cms-forms/cms-forms/cms-forms-items/cms017339

What it does:

Formally signs you up for Part B and lets you request your desired coverage start month.

  • Fill in the remarks section with: “I want Part B coverage to begin (MM/YY)”

  • Submit it with your CMS‑L564 and any employer or coverage proof.

✅ Step-by-Step Process

StepAction1) As soon as your employer coverage ends, request employer-completed CMS‑L564. 2)Complete the personal details on CMS‑L564 (Section A). 3)Fill out CMS‑40B, requesting your preferred Part B start date in remarks. 4)Gather proof of employer coverage (if needed). 5)Submit both forms plus supporting docs to your local Social Security office by mail, fax, or in person. 6)Or apply online through SSA.gov under “Apply Online for Medicare Part B During a SEP.” Upload digital copies of forms and evidence.

Your coverage generally begins the first day of the month after you apply (but I have seen it take up to 8 weeks)

You may request retroactive coverage (up to 6 months) in the remarks.

⏳ Timing: Don’t Miss the 8‑Month Window

You have 8 months after losing job-based health coverage (or employment ends) to enroll in Part B without penalties.

If you sign up while you’re still working or in the first month after coverage ends, you may request to delay your Part B start date by up to 3 months, if that helps coverage coordination.

FAQs

Q1: What if my employer won’t fill out CMS‑L564?

A: Submit as much Section B info as you can and attach proof like pay stubs, insurance premium records, or insurance ID cards

Q2: Can I apply online?

A: Yes! SSA.gov offers an online application for Part B during SEP. Upload your CMS‑40B, CMS‑L564, and verification docs electronically.

Q3: When will coverage start?

A: Normally the month after submission. You may request retroactive coverage (no earlier than 6 months back from the date you apply).

Q4: What if I miss the 8‑month window?

A: You’ll no longer qualify for SEP, and may need to wait until General Enrollment Period (Jan 1‑Mar 31), together with potential late penalties.

Q5: Do I need Part A first?

A: Yes, you must have Part A (either premium-free or purchased). If you don’t have it, you’ll need to sign up for Part A and Part B (form CMS‑10797 or CMS‑40B for general).

Q6: How much does Part B cost in 2025?

A: The standard premium is about $185/month in 2025, with a deductible (~$257/year). Medicare typically covers 80% of eligible services after deductible.

Final Tips

  • Don’t delay—start the forms process right when employer coverage ends.

  • Keep copies of EVERYTHING you submit and ask for proof of submission.

  • If anything’s unclear, call 1‑800‑772‑1213 (Social Security) or 1‑800‑MEDICARE.

  • Once accepted, you’ll get your Medicare card and welcome packet in the mail—follow instructions on next steps like choosing Medigap, a Part D drug plan, or Medicare Advantage.

  • The CMS‑40B and CMS‑L564 is straightforward—just follow the steps, submit on time, and you’ll have Part B coverage without penalties.

  • If you’d like help to fill out the forms line by line or, I’m happy to help!