How Do I Sign Up For Medicare If I Am Still Working At 65

If your employer has 20 or more employees, you can delay Part B without penalty and just sign up for premium-free Part A online; if your employer is smaller, you must sign up for both Part A and Part B during your Initial Enrollment Period to avoid lifelong late penalties.

Check your company size before you sign up for Medicare

The 20-employee threshold is the single deciding factor. It determines whether you must enroll now or can safely wait. The Centers for Medicare & Medicaid Services (CMS) bases this rule on the size of your organization. It does not matter whether you work full-time, part-time, or are a contractor. If your company has 20 or more workers, your group health plan is considered the “primary payer”. It pays first. Medicare pays second, if at all. In that scenario, you are free to delay Part B without any late surcharge. You can also delay Part D for prescription drugs. Your workplace plan counts as “creditable coverage” that matches or exceeds Medicare’s standards.

If your organization has fewer than 20 people, the opposite is true. Medicare becomes the primary payer. Your workplace plan pays second. That means if you skip Part B now, you will have a gap in primary protection. When you eventually sign up, you will pay a 10% surcharge on Part B premiums for every full 12-month period you delayed. That surcharge is permanent, not temporary. So before you do anything else, ask your HR department for the exact headcount. Get it in writing. A single email confirming “we have 34 employees” is enough to save you thousands later.

When you can delay Part B

If your organization has 20 or more workers, you can enroll only in Part A online at Social Security’s website. Skip Part B entirely. Part A is premium-free for most people who have worked at least 10 years. There is no monthly cost. You can sign up for Part A at any time after you turn 65, even while still working. It will act as secondary insurance. It covers things like hospital stays and skilled nursing that your group plan might not fully cover. To do this, visit ssa.gov. Create or log in to your My Social Security account. Follow the prompts under “Medicare” and “Sign Up for Part A.”

The specific form your company fills out later is called CMS-L564, the “Request for Employment Information.” You will need this when you eventually retire and want to enroll in Part B without a surcharge. Your organization must complete Section A. This confirms you had group health protection after you turned 65. You complete Section B with your personal details. Keep a copy of that form with your tax records. You will need it to prove you had creditable protection during the entire delay period. Without it, Social Security may assume you had no protection and retroactively charge you late fees.

The mistake that triggers a lifelong surcharge

The most common failure case involves people with small-group insurance or COBRA. They assume they have creditable protection and delay enrollment. Then they face permanent premium surcharges and gaps in their benefits. Here is how it happens. You work for a company with 12 people. Your HR manager says “we have great insurance, don’t worry about Medicare yet.” You believe them. But with under 20 workers, your workplace plan is the secondary payer. It only pays after Medicare. If you skip Part B, you have no primary protection. Your group plan will deny most claims. You will be responsible for the full bill. When you finally realize the mistake and enroll in Part B, the fee is 10% of the Part B premium for every 12-month period you were eligible but unenrolled. That is a lifetime surcharge. It compounds every year.

COBRA is an even trickier trap. COBRA is not active employment coverage. It is a continuation of your old company’s plan. It does not count as creditable protection for Medicare purposes unless you are also working for that same company. If you retire at 65 and take COBRA, you must still enroll in Part B within your Initial Enrollment Period. That period lasts 7 months, starting 3 months before your 65th birthday. If you rely on COBRA as your only protection, you will face the same 10% fee. You will also have a gap in benefits because COBRA typically pays secondary to Medicare, not primary. The rule is simple. If you are 65 or older, Medicare is your primary payer unless your company has 20+ workers and you are actively working for them. COBRA never counts.

Frequently Asked Questions

What if I have a spouse who is still working and I am on their plan?

You can delay Part B without a surcharge if your spouse’s company has 20 or more workers. You must be covered under their plan as a dependent. The same CMS-L564 form applies. Your spouse’s company fills it out. If that organization has fewer than 20 people, you must enroll in Part B during your Initial Enrollment Period.

Do I need to sign up for Part D if I have drug benefits through work?

If your company’s drug plan is “creditable,” you can delay Part D without a fee. This means it pays at least as much as Medicare’s standard. Your organization must give you a notice of creditable protection each year. If they do not, ask for it in writing. You will need that notice later to prove you had protection.

What happens if I miss my Initial Enrollment Period entirely while working?

If you miss the 7-month window around your 65th birthday, you must wait for the General Enrollment Period. This runs from January 1 to March 31. Your protection starts July 1. You will pay the 10% late fee for Part B for every 12-month period you delayed. You will also have a gap in benefits in the meantime. The only exception is if you qualify for a Special Enrollment Period. This applies if you had creditable protection from a company with 20+ workers. But you must still enroll within 8 months of that protection ending.

Can I enroll in Part A and Part B at the same time online if I am still working?

Yes, but only if you want both. If you have a small organization, you must enroll in both online at ssa.gov during your Initial Enrollment Period. If you have a large organization, you can enroll in Part A only online. Then use the CMS-L564 form later for Part B. Social Security’s online portal clearly shows a checkbox for “Part A only” versus “Part A and Part B.” Do not select both unless you are sure you need Part B immediately.

Navigating the decision to sign up for Medicare while still working at 65 comes down to one critical, often misunderstood detail: your employer’s headcount, specifically, whether you have 20 or more workers versus fewer than 20, is the sole trigger that flips your group plan from primary to secondary payer, and COBRA never counts as creditable coverage for delaying Medicare, no matter what your HR department claims. For a deeper look at how these rules fit into your overall strategy, explore the broader topic of healthcare & medicare: what to know and how to handle it, which covers the full landscape of enrollment, penalties, and coordination of benefits.