It's important to understand how Medicare coordination of benefits works if you’re covered by Medicare and another healthcare plan. In short, this process outlines which insurer is responsible for paying first when there are overlapping benefits between them. Let’s take a closer look at this process, how it works, and what you need to know.
What Is Medicare Coordination of Benefits (COB)?
Medicare coordination of benefits (COB) applies when someone receives coverage from Medicare and another form of health insurance. Under COB rules, the secondary insurance coverage kicks in after the primary insurer pays its share. This often includes payments for deductibles, coinsurance, or copayments.
If the individual has Medicare and employer coverage, then Medicare will be primary when the employer has 20 or less employees. If the employer has more than 20 employees, then employer coverage is primary.
Other types of coverage such as Medicaid, TRICARE, Medigap, and retiree coverage from a former employer may also become the secondary payer. If you're unsure whether your other coverage is primary or secondary to Medicare, then you can always contact your benefits administrator.
How Coordination of Benefits Works
When you have two overlapping health insurance plans, each one has its own coordinator. The coordinators for each plan communicate with each other to figure out who should pay first. This process is known as coordination of benefits.
There are several things the coordinators will assess when determining who should pay first. For example, they'll look at who is considered the primary insurer under each plan. They'll also figure out whether one plan considers the other to be a secondary insurer. Ultimately, the coordinators will work together to decide which insurer handles which benefits.
Medicare-Covered Services
Typically, if you have Original Medicare (Part A and Part B) and another form of health insurance (such as through an employer), then both plans will cover medical services if Medicare is the primary payer. These services may include:
- Preventive care: Screenings, vaccinations, and counseling to prevent illness or disease,
- Diagnostic tests: X-rays, MRIs, and CT scans used to diagnose a condition,
- Inpatient care: Care received while staying in a hospital overnight,
- Outpatient care: Services received outside of a hospital setting (e.g., at a doctor's office),
- Emergency care: Treatment received for acute conditions that require immediate attention,
- Other medically necessary services: Any services necessary to treat an illness or injury that meet certain standards set by Medicare, and
- Durable medical equipment: oxygen tanks, wheelchairs, walkers, and other forms of mobility assistance.
What Does Coordination of Benefits Mean for You?
The specifics of your COB will differ depending on your unique situation. However, there are a few key things to keep in mind. For one, you usually won’t have to pay anything out of pocket if you see a doctor who accepts assignment from Medicare.
This means the doctor agrees to accept the Medicare-approved amount as payment in full. Remember that you’ll still be responsible for any deductibles or copayments required by your supplemental insurance policy.
In some cases, you may also need to submit a claim form to your supplemental insurer for reimbursement for covered services. Be sure to check with them ahead of time to find out what their claims process entails. This will ensure there are no surprises when you get your final bill.
We're Always Here to Help
Medicare and coordination of benefits can both be confusing. However, by recognizing how the process works and what your coverage is, you’ll rest assured that your claims are correct and you're getting all the benefits you deserve.
If you have any questions about Medicare, coverage options, or coordination of benefits, then please feel free to give us a call, reach out via email, or send us a message online. We’re always available to answer your questions and provide one-on-one support whenever you need it.









