Do I have to enroll in Medicare at 65 if I'm still working?

Not always. If your employer has 20 or more employees and offers creditable group health coverage, Medicare is secondary and you can delay Part B (and often Part D) without a late-enrollment penalty. If the employer has fewer than 20 employees, Medicare is primary — you usually should enroll at 65 or risk gaps and denied claims.

Should I take premium-free Part A while I'm still working?

Usually yes, unless you contribute to an HSA. Part A is free if you have 40+ work quarters, so it can act as secondary coverage. But once you enroll in Part A (even retroactively up to 6 months), you can no longer contribute to a Health Savings Account.

How does the Special Enrollment Period (SEP) work when I retire?

When you (or your spouse) lose active employer group coverage, you get an 8-month Special Enrollment Period to sign up for Part B without a late penalty. Part B coverage starts the month after you enroll. Enroll BEFORE your group coverage ends to avoid a gap.

What is a CMS-L564 form and why do I need it?

Form CMS-L564 (Request for Employment Information) is what your employer signs to prove you had creditable group coverage since turning 65. You submit it with form CMS-40B when you enroll in Part B during your SEP — it's what lets you avoid the late-enrollment penalty.

Can I contribute to an HSA while on Medicare?

No. Once any part of Medicare (including premium-free Part A) is active, you cannot make new HSA contributions. You can still spend existing HSA funds tax-free on qualified medical expenses, including Medicare premiums for Parts B, D, and Medicare Advantage.

Is COBRA considered creditable coverage for delaying Part B?

No. COBRA is NOT considered active employer coverage by Medicare. If you rely on COBRA past 65 and skip Part B, you'll owe a lifetime late-enrollment penalty. Enroll in Part B when your active group coverage ends, not when COBRA ends.

What about my spouse's coverage — can I stay on their employer plan?

Yes, if your spouse is still actively working and their employer has 20+ employees, you can delay Part B under their group coverage. The same 8-month SEP applies when their coverage ends. If they retire before you turn 65, or their employer has fewer than 20 employees, different rules apply — book a call.

Working Past 65 in Texas? How Medicare Coordinates With Your Employer Coverage

When to take Part A, when to delay Part B, HSA rules, CMS-L564, and the 8-month Special Enrollment Period — without paying a lifetime late-enrollment penalty.

Quick answerIf your employer has 20+ employees and offers creditable group coverage, you can safely delay Part B (and often Part D) past 65 with no penalty. When you retire or the group coverage ends, an 8-month Special Enrollment Period opens to sign up for Part B using forms CMS-40B and CMS-L564. If your employer has fewer than 20 employees, Medicare is primary — enroll at 65 to avoid gaps and denied claims.

Working past 65? Get one free call before you decide about Part B.

One wrong move (COBRA instead of Part B, missing a CMS-L564, HSA contributions after Part A) can cost you thousands — for life. We'll map your options in 20 minutes at no cost.

Book my planning call

Or call now — no wait 800-214-8976

Employer with 20+ employees

Medicare is secondary

Group plan pays first, Medicare pays second.
Delay Part B — no late-enrollment penalty.
Take Part A if you don't have an HSA (it's free).
8-month SEP opens the month group coverage ends.

Employer with fewer than 20 employees

Medicare is primary

Medicare pays first — the group plan pays second (if at all).
Skipping Part B means the group plan may deny claims Medicare would have covered.
Enroll in Part A and Part B during your Initial Enrollment Period.
Confirm coordination-of-benefits rules with HR in writing.

HSA warning: stop contributions before Part A takes effect

You cannot contribute to an HSA once any part of Medicare is active — including premium-free Part A. If you enroll in Medicare after age 65, Part A is backdated up to 6 months. Stop HSA contributions 6 months before your Medicare effective date to avoid IRS penalties on excess contributions.

Existing HSA funds can still be spent tax-free on qualified medical expenses — including Part B, Part D, and Medicare Advantage premiums (but not Medigap premiums).

6-Step Working-Past-65 Medicare Plan

1
Confirm employer size and coverage
Ask HR two questions: (1) Does the employer have 20+ employees? (2) Is the group plan considered creditable coverage for Medicare? Get the answer in writing.
2
Decide about premium-free Part A
If you don't contribute to an HSA, enrolling in Part A at 65 is usually safe and free — it becomes secondary coverage. If you do use an HSA, stop contributions before Part A takes effect (including up to 6 months of retroactive coverage).
3
Delay Part B (if eligible)
With 20+ employee creditable group coverage, you can safely delay Part B. Do NOT enroll in Part B at 65 — you'd pay premiums for coverage you don't need and lose your Medigap Open Enrollment window when you actually retire.
4
Skip Part D if group drug coverage is creditable
If your employer plan's drug coverage is creditable (they'll send a notice each September), delay Part D too. Keep every creditable-coverage notice — you'll need them to avoid the Part D late-enrollment penalty later.
5
Plan the exit 60–90 days before retirement
Book a Medicare planning call. Request form CMS-L564 from HR. Choose Medigap vs Advantage. Line up your Part D plan. Aim for zero gap between group coverage ending and Medicare starting.
6
Enroll in Part B using your SEP
Submit forms CMS-40B and CMS-L564 to Social Security. Part B starts the month after you enroll (you can request it start up to 3 months later). Your one-time 6-month Medigap Open Enrollment begins the day Part B is effective.

Book my planning call or call 800-214-8976

The COBRA trap — read this before you accept COBRA at 65

COBRA is not considered active employer coverage by Medicare. If you retire, take COBRA, and skip Part B thinking you're covered:

Your 8-month SEP starts the day active coverage ended — not the day COBRA ends.
If you enroll in Part B after the SEP expires, you'll owe a lifetime 10%-per-year late-enrollment penalty.
COBRA also may become secondary to Medicare once you turn 65 — the COBRA plan can legally refuse to pay what Medicare would have paid.

Rule of thumb: at 65 or older, enroll in Part B when your active group coverage ends — treat COBRA only as short-term wraparound if useful.

More traps to sidestep: the 10 costliest turning-65 Medicare mistakes →