Employer Health Coverage and Medicare

We can help you understand how Medicare pairs with employer health plans.

How They Work Together

When people are Medicare-eligible and still employed, the biggest mistake they make is simply ignoring Medicare.

Medicare can work alongside employer-sponsored health insurance, but how the two coordinate depends largely on the size of the employer. The key question is which coverage pays first: Medicare or the employer group health plan.


The coverage that pays first is called the primary payer, while the coverage that may help with remaining covered costs is called the secondary payer.

Here are the questions we can help navigate:

  • When should I start planning for health care in my retirement?
  • Should I enroll in an individual Medicare option or remain on the employer plan?
  • Can Medicare work with my employer plan?
  • How can I care for my non-Medicare-eligible dependents?
  • What steps do I need to take once I decide to retire to ensure I have a solid health care plan?

Businesses with Fewer than 20 Employees

When a business has fewer than 20 employees, Medicare generally becomes the primary payer once an employee turns 65 and is eligible for Medicare. The employer group health plan becomes the secondary payer.


Here’s how it works:


  • Medicare pays first for covered healthcare services.
  • The employer health plan pays second, potentially covering some remaining costs depending on the plan design.
  • If an employee does not enroll in Medicare Part B when first eligible, the employer plan may pay as though Medicare had paid first, which can leave the employee responsible for significant out-of-pocket costs.


Important Rules for Employees Age 65+

Even if they remain on the employer plan, employees should typically enroll in:

  • Medicare Part A (hospital coverage)
  • Medicare Part B (medical coverage)


Why This Matters

Many people mistakenly believe they can delay Medicare because they still have employer coverage. However, with small employer groups, delaying Medicare Part B can result in:

  • Coverage gaps
  • Late enrollment penalties
  • Higher medical expenses


Employee Choices

Employees may choose to:


  • Keep both Medicare and the employer plan
  • Drop the employer plan and move fully to Medicare
  • Add a Medicare Supplement or Medicare Advantage plan depending on their needs

How Do You Decide?

The best strategy depends on:



  • Prescription coverage
  • Monthly premium costs
  • Provider networks
  • Retirement timing
  • Spouse/dependent coverage needs


Because these decisions can affect both healthcare costs and retirement planning, it’s important to review all options carefully with a knowledgeable Medicare and benefits advisor.

Important note:  When you decide to stop working, if you are over age 65, do not assume you should take COBRA. 

COBRA is not considered "creditable coverage" in the Medicare space, and you may incur penalties. You also lose your special enrollment opportunity, and will need to wait until open enrollment for Medicare.  Contact me for detailed guidance on COBRA-related decisions.

Businesses with 20+ Employees

When a business has 20 or more employees, the employer group health plan generally becomes the primary payer once an employee turns 65 and is eligible for Medicare. Medicare then becomes the secondary payer.


Here’s How It Works:


  • The employer health plan pays first for covered healthcare services.
  • Medicare pays second, potentially helping cover some remaining eligible costs depending on the plan design.
  • Employees who are actively working and covered under a large employer group health plan may be able to delay enrolling in Medicare Part B without incurring a late enrollment penalty.


Important Rules for Employees Age 65+

For employers with 20 or more employees:


Employees may choose to:


  • Enroll in Medicare Part A (hospital coverage), which is often premium-free
  • Delay Medicare Part B (medical coverage) while covered by active employer insurance


Many employees keep their employer coverage because it may provide:


  • Comprehensive medical benefits
  • Prescription drug coverage
  • Lower out-of-pocket costs through employer contributions


Why This Matters

Many people approaching Medicare eligibility are unsure whether they should enroll in Medicare while still working. With larger employer groups, employees often have more flexibility, but it’s still important to evaluate all coverage options carefully.


Delaying Medicare Part B may be appropriate for some individuals, but the decision should consider:


  • Monthly premium costs
  • Provider access and networks
  • Prescription drug coverage
  • Health savings account (HSA) contributions
  • Retirement timing
  • Spouse and dependent coverage needs


When employer coverage eventually ends, employees may qualify for a Special Enrollment Period to enroll in Medicare Part B without penalty.