HR’s Top 3 Medicare FAQs

What Medicare Questions Do HR Professionals Get Asked Most?

Direct answer: Three questions come up consistently as employees approach 65: when they need to actually enroll in Medicare to avoid a penalty, how Medicare coordinates with employer health coverage once they’re eligible, and when HSA contributions need to stop. Getting accurate answers to these three — not just generally right, but precisely right — is what protects employees from real, permanent financial consequences, since several of the rules involved carry lifelong penalties if handled incorrectly.

When Should Employees Enroll in Medicare to Avoid Penalties?

Most employees should enroll during their Initial Enrollment Period — the seven-month window centered on their 65th birthday. Beyond that baseline, the right guidance depends entirely on employer size:

• Fewer than 20 employees: Medicare generally becomes primary coverage at 65, and employees typically need to enroll at that point regardless of continued employer coverage, or risk a penalty.
• 20 or more employees: Employees can generally delay Part B enrollment without penalty while actively employed and covered by the employer’s plan. Once they retire or lose that coverage, they qualify for a Special Enrollment Period to enroll penalty-free.

Late enrollment penalties are genuinely permanent, not temporary consequences:

• Part A (for those who don’t qualify for premium-free coverage): a 10% surcharge added to the premium, applied for twice the number of years the employee delayed enrollment.
• Part B: roughly 10% added to the premium for each full 12-month period of delay — a permanent increase lasting as long as the employee has Part B.
• Part D: roughly 1% of the national base beneficiary premium for every month without creditable drug coverage, also permanent for as long as the employee maintains Part D.

These penalties don’t expire — they remain attached to the premium for as long as the employee is enrolled, which for most people means for life. Clear guidance about these windows genuinely saves employees from an unnecessary, lasting cost.

How Does Medicare Work With Employer Health Plans After 65?

Employees can maintain both Medicare and employer-sponsored coverage simultaneously if they continue working past 65 — coordination depends on company size:

• 20 or more employees: The employer plan pays first (primary), with Medicare acting as secondary coverage.
• Fewer than 20 employees: Medicare becomes primary, with the employer plan secondary. Employees generally need to enroll in Medicare to avoid a coverage gap.

Whether an employee should keep employer coverage or transition fully onto Medicare typically comes down to:

• Satisfaction with the employer plan compared to available Medicare options.
• Real cost comparison between employer coverage and Medicare (potentially with Medigap added).
• Whether they need to maintain employer coverage for dependents, since Medicare only covers the employee individually.
• Whether they’re a high earner who’d face an IRMAA surcharge by enrolling in Medicare before actually retiring.

Prescription drug coverage follows a similar comparison — employees should weigh their employer plan against Medicare Part D directly for their specific medications. For complex individual situations, encourage employees to speak with a licensed Medicare advisor rather than relying on general guidance alone.

When an employee does transition off employer coverage, they’ll need Form CMS-L564 to document their prior creditable coverage. For the complete walkthrough — including a detail that trips people up, that this form must be submitted together with the actual Part B application, not on its own — see our complete guide to Form CMS-L564.

When Should HSA Contributions Stop Before Medicare Enrollment?

Employees need to stop contributing to a Health Savings Account before the month their Medicare coverage actually begins. Contributions made after enrollment — including during any retroactive coverage period — are treated as excess contributions, triggering an ongoing annual excise tax until they’re corrected.

A detail worth emphasizing clearly to employees: Medicare Part A enrollment can be backdated up to six months once someone actually applies. This means the safe cutoff isn’t “six months before coverage starts” — it’s roughly six months before the employee actually applies, since that application date is what determines the retroactive window. HR teams commonly recommend stopping contributions at least six months ahead of the planned enrollment date, though the exact right timing depends on individual circumstances, including Social Security benefit timing. Employees who retire mid-year can generally prorate their annual HSA contribution based on the months they were actually HSA-eligible. For situations requiring correction, employees should contact their HSA provider to remove excess contributions and consult a tax professional.

Can HSA Funds Still Be Used After Enrolling in Medicare?

Yes — and this deserves more precision than a blanket statement either way. Existing HSA funds remain usable tax-free for qualified medical expenses after Medicare enrollment, including:

• Deductibles and copayments
• Services Medicare doesn’t cover, like certain dental or vision care
• Prescription medications

Here’s the correction worth making clearly: HSA funds can be used tax-free to pay Medicare Part A, B, C (Medicare Advantage), and D premiums — this is genuinely useful and often underused. The specific exclusion is Medigap premiums, which the IRS does not treat as a qualified expense for HSA purposes. If an employee withdraws HSA funds to pay a Medigap premium, that withdrawal is taxed as ordinary income. This distinction matters directly for anyone comparing Medigap against Medicare Advantage with HSA funds available — it’s a real, asymmetric tax factor worth including in that comparison, not a minor footnote.

What Should HR Communicate Clearly to Employees?

• The actual cutoff timing for stopping HSA contributions, accounting for the six-month retroactive Part A backdating risk, not just a generic “six months before” rule of thumb.
• Which Medicare-related premiums HSA funds can and can’t cover — correcting the common assumption that no Medicare costs qualify.
• The real consequences of excess contributions and the process for correcting them if they occur.

What Role Can HR Play in Supporting Employees Through This Transition?

• Host informational sessions for employees nearing 65, covering enrollment timing, penalties, and employer-size-specific rules.
• Build a resource library — fact sheets, enrollment guides, and contacts for local Medicare assistance.
• Bring in independent Medicare advisors periodically to address individual circumstances directly.
• Create a simple enrollment checklist to help employees track deadlines and required forms, including CMS-L564.
• Explain benefit coordination clearly — specifically which plan pays first, based on company size, since this is a common point of confusion.

Bottom Line

Getting Medicare guidance right for employees nearing 65 means precision, not general reassurance — the difference between accurate and slightly-off information can mean a permanent penalty or a missed tax-advantaged payment option. HR teams are well-positioned to provide clear, proactive education on enrollment timing, benefit coordination, and HSA rules, while directing genuinely complex individual situations to a licensed Medicare advisor. Your effort to simplify this process for employees has a real, lasting financial impact on their retirement.

Key Takeaways

• Employer size (20+ employees vs. fewer) determines whether employees can delay Medicare Part B without penalty while still working.
• Late enrollment penalties for Parts A, B, and D are permanent, not temporary, lasting for as long as the employee maintains that coverage.
• HSA contributions must stop before Medicare coverage begins, and Part A’s six-month retroactive backdating means the safe cutoff is based on the application date, not just the coverage start date.
• HSA funds can be used tax-free to pay Medicare Part A, B, C, and D premiums — a fact commonly and incorrectly assumed not to apply to any Medicare costs.
• The one real exclusion is Medigap premiums, which the IRS doesn’t treat as a qualified HSA expense.
• Form CMS-L564 is required when an employee transitions from employer coverage to Medicare, and must be submitted alongside the Part B application itself.

FAQ

Can employees delay Medicare Part B if they’re still working at 65?
Depends on employer size — generally yes without penalty for companies with 20 or more employees and qualifying coverage; generally no for smaller employers.

Can HSA funds pay Medicare premiums?
Yes, for Part A, B, C, and D premiums — a commonly misunderstood point. The exclusion is specifically Medigap premiums, which don’t qualify for tax-free HSA payment.

When should employees stop HSA contributions before enrolling in Medicare?
Generally at least six months before their planned enrollment application date, accounting for Part A’s retroactive backdating, not just the coverage start date.

What happens if an employee contributes to an HSA after enrolling in Medicare?
The contributions are considered excess and trigger an ongoing annual excise tax until corrected with the HSA provider.

What form is needed when an employee transitions from employer coverage to Medicare?
Form CMS-L564, which must be submitted together with the Part B enrollment application, not on its own.

How does Medicare coordinate with employer coverage for employees over 65?
For companies with 20 or more employees, the employer plan pays first; for fewer than 20, Medicare generally becomes primary.