If you plan to continue working past your 65th birthday, you are far from alone. According to the Bureau of Labor Statistics, approximately 10 million workers—representing nearly 18% of the 65-and-older population—are still actively participating in the workforce. However, continuing to work can create a confusing crossroads when it comes to your healthcare coverage.
A widely cited CNBC article titled “If you’re still working when you turn 65, be sure to avoid costly mistakes with Medicare” highlighted a critical pitfall: the false belief that simply because you have employer health insurance, you don’t need to worry about Medicare. Assuming you can indefinitely delay Medicare enrollment without consequences is one of the most expensive financial planning mistakes older Americans make.
While not everyone is required to enroll in Medicare at the age of eligibility, navigating the exceptions requires precision. A misstep could saddle you with lifelong late-enrollment penalties, gaps in your health coverage, and devastating out-of-pocket medical expenses. With guidance from the Centers for Medicare & Medicaid Services (CMS) and Medicare.gov, this comprehensive guide will help you understand the rules of the road, protect your wealth, and seamlessly transition into your Medicare years.
The General Rule: Your Initial Enrollment Period (IEP)
For most Americans, eligibility for Medicare begins at age 65. The standard protocol for enrollment revolves around your Initial Enrollment Period (IEP). Unless you qualify for a specific exemption, you are granted a seven-month enrollment window:
- Three months before the month of your 65th birthday.
- The month of your 65th birthday.
- Three months after your birthday month.
If you fail to enroll during this seven-month window and you do not have qualifying health coverage, you will face lifelong financial penalties when you eventually sign up. But what constitutes “qualifying coverage” when you are still working? The answer largely depends on the size of your employer.
The Employer Size Exception: 20 Employees is the Magic Number
The rules for delaying Medicare depend entirely on how many people your company employs.
Large Employers (20 or More Employees)
If you receive health insurance through an employer with 20 or more employees, your group health plan is considered primary coverage. In this scenario, you are generally allowed to delay enrolling in Medicare Part B (outpatient care) and Part D (prescription drugs) without facing late penalties until you retire or lose that coverage—whichever comes first.
Many workers at large firms choose to delay Part B (which carries a monthly premium) but go ahead and enroll in Medicare Part A (hospital insurance). For individuals with at least a 10-year work history of paying into the program through payroll taxes, Part A does not have a premium. Enrolling in Part A costs you nothing and serves as a secondary payer if you are hospitalized, potentially covering deductibles or coinsurance that your employer plan misses.
Small Employers (Fewer Than 20 Employees)
If your company has fewer than 20 employees, the rules flip entirely. Once you turn 65, Medicare becomes your primary insurance, and your employer’s group plan becomes secondary.
This is critical: If you work for a small business, you should sign up for Medicare at age 65, whether or not you remain on the company’s health plan. If you fail to enroll, your employer’s insurance carrier can legally refuse to pay for your primary medical claims, leaving you personally responsible for catastrophic hospital or outpatient bills.
Furthermore, remaining on a small employer’s group plan as secondary insurance might not make financial sense. Studies show that employees at small firms often bear a heavier burden of healthcare costs. While the average premium for single coverage through employer-sponsored health insurance hovers around $7,470—with employees contributing an average of 17% ($1,243)—small business employees frequently pay significantly more. It is often more cost-effective for a 65-year-old at a small firm to drop their employer coverage entirely and transition fully to Medicare (pairing it with a Medigap and Part D plan, or a Medicare Advantage Plan).
The HSA Trap: High-Deductible Health Plans and Medicare
One of the most complex traps for working seniors involves Health Savings Accounts (HSAs). If you have a high-deductible health plan (HDHP) through your employer and contribute to an HSA, you must stop all contributions once you enroll in any part of Medicare, including the premium-free Part A.
Under IRS rules, you cannot contribute to an HSA if you are enrolled in Medicare. Doing so will trigger tax penalties.
Even more dangerously, if you delay Medicare past age 65 and later decide to enroll when you retire, Medicare Part A coverage will be applied retroactively for up to six months (but no earlier than your 65th birthday). To avoid tax penalties, the general rule of thumb is that you must stop contributing to your HSA at least six months before you officially apply for Medicare or draw Social Security benefits.
The Cost of Waiting: Lifelong Late-Enrollment Penalties
It cannot be overstated: Medicare late-enrollment penalties last for the rest of your life. If you do not have creditable employer coverage and you miss your Initial Enrollment Period, you will pay these surcharges for as long as you have Medicare.
- The Part B Penalty (Outpatient Coverage): You will be penalized 10% of the standard Part B premium for every full 12-month period you were eligible for Part B but did not enroll. For 2026, the standard Part B premium has risen to $202.90 per month. If you wait three years to sign up without creditable coverage, you will pay an extra 30% on top of your premium every single month, for life.
- The Part D Penalty (Prescription Drug Coverage): The Part D penalty is calculated as 1% of the national base beneficiary premium ($38.99 in 2026) multiplied by the number of full, uncovered months you didn’t have Part D or creditable prescription drug coverage. This penalty is added to your monthly premium permanently.
Note: Retiree health plans and COBRA are NOT considered creditable current employer coverage for the purpose of delaying Medicare Part B. If you are on COBRA, you must sign up for Medicare when you turn 65 to avoid the penalty.
Consider Your Younger Spouse
Deciding whether to keep your employer plan or transition to Medicare isn’t just about you—it’s also about your dependents. If you have a younger spouse who relies on your employer-sponsored health insurance, leaving your company plan for Medicare could leave them uninsured.
Unlike employer group health plans that cover entire families, spouses are required to qualify on their own for Medicare, regardless of your own eligibility. If you decide to transition to Medicare, you will need to evaluate how your spouse will obtain coverage until they turn 65, whether through their own employer, the Affordable Care Act (ACA) marketplace, or COBRA.
Evaluating Your Medicare Coverage Options
Once you decide to enroll in Medicare, you face another major fork in the road: Traditional Medicare versus Medicare Advantage. Making sure you understand these two distinct paths is vital to your healthcare and financial planning.
1. Traditional Medicare (Parts A & B) with a Medigap Policy
Traditional Medicare consists of Part A (hospitals) and Part B (doctors and outpatient care). Because Traditional Medicare covers only about 80% of approved costs, most beneficiaries pair it with a Medicare Supplement plan (Medigap) to cover the remaining 20% of copays and deductibles, along with a standalone Part D plan for prescription drugs.
- The Benefit: The primary advantage of Traditional Medicare is the ultimate freedom of choice. You can see any doctor, specialist, or hospital in the United States that accepts Medicare, without needing a referral or worrying about network restrictions.
2. Medicare Advantage (Part C)
Today, roughly half of all individuals opt to get their Part A and Part B benefits delivered through a Medicare Advantage Plan (Part C) rather than through Traditional Medicare. These plans are offered by private insurance companies approved by Medicare.
- The Benefit: Medicare Advantage plans bundle everything together. They typically include prescription drug coverage (Part D) and may offer extra benefits that Traditional Medicare doesn’t cover, such as dental, vision, hearing, and gym memberships. They often have low or $0 additional monthly premiums.
- The Trade-off: The caveat is that you are usually restricted to an HMO or PPO network of local doctors and hospitals, and you may need referrals to see specialists.
Knowledge Is Power: Plan Your Next Steps
Transitioning into Medicare while you are still working involves juggling employer HR policies, IRS tax codes regarding HSAs, and strict CMS deadlines. The cost of a mistake isn’t just a one-time fee; it’s a permanent reduction in your retirement income due to lifelong penalties.
If you remain with your current coverage and delay all or parts of Medicare, make certain that the plan is considered “qualifying coverage” for both Parts B and D. If you’re unclear if you need to enroll, ask your human resources department or your insurance carrier to confirm in writing.
Learn More with McNair Dallas Law
At McNair Dallas Law, we understand that healthcare planning is a critical pillar of your overall estate and retirement strategy. To help you make sense of your options, we have released two comprehensive video guides on the McNair Dallas Law YouTube Page. These videos compare and contrast the intricacies of Traditional Medicare with Medicare Advantage Plans, breaking down the financial and medical implications of each choice.
Visit the McNair Dallas Law YouTube Channel to watch these videos and take the next step in empowering your retirement planning. For personalized legal and estate planning guidance, book a call today.
Disclaimer: This article is intended for informational and educational purposes only and does not constitute legal or financial advice. Medicare rules and premium amounts (such as the 2026 figures referenced) are subject to annual changes by CMS. Please consult with a qualified elder law attorney, financial advisor, or Medicare specialist regarding your specific situation. to avoid costly mistakes with Medicare”
