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Coordination of benefits (COB) allows you to have multiple health insurance plans. COB allows insurers to determine which insurance company will be the primary payer and which will be the secondary if you have two separate plans. It also makes sure insurance companies don’t duplicate payments or reimburse for more than the health care services cost.

Key Takeaways

  • Health insurance plans have a coordination of benefits system when the member has multiple health plans.
  • The health plan that pays first depends on the type of plan, size of the company and location.
  • The two insurers pay their portions of the claim and then the member pays the rest of the bill.

What is coordination of benefits?

Coordination of benefits creates a framework for the two insurance companies to coordinate benefits so they pay their fair share when both plans pay. COB decides which is the primary insurance plan and which one is secondary insurance. You can think of the secondary payer as supplemental coverage to help you pay for out-of-pocket costs.

How does coordination of benefits work?

If you use coordination of benefits for health insurance, the primary insurance pays its share of your health care costs first. Then, the secondary insurance plan will pay up to 100% of the total cost of health care, as long as it’s covered under the plan. Neither plan will pay more than 100% of the total health care costs, so you won’t get double the benefits if you have multiple health insurance plans.

Coordination of benefits rules

COB rules vary for each individual and depend on the size and type of your plans and what state you live in, as many states also have different laws in place. Additionally, large employers may have their own COB rules for medical claims.

  • Medicaid and Medicare: Typically, Medicaid only pays as a last resort when there are multiple plans. But medicare can be primary or secondary, depending on the circumstances. For instance, Medicare is the primary payer if the other insurer is a small business, but it’s secondary when the other payer is a large company.
  • Employer-sponsored plans: If you and your spouse have employer health plans, your employer is generally the primary payer for you and your spouse’s plan is secondary.
  • Workers’ compensation: The worker’s comp pays first and your health insurance plan would is considered secondary.
  • Veterans Administration (VA) and a private health insurance plan: VA is not considered a health insurance plan. Instead, the VA bills public or private health insurance providers for care, services, prescriptions and supplies. So, if your spouse has a health insurance plan, it would be your health plan.
  • Military coverage (TRICARE) and other health insurance: TRICARE is considered secondary to all other health plans, except Medicaid, TRICARE supplements, state crime compensation programs and other specified federal government programs. Note: If you are on active duty, you can’t use any other health insurance. TRICARE is your only health insurance coverage.

How the coordination of benefits system works

Here’s an example of how the process works:

  • Let’s say you visit your doctor and the bill comes to $100.
  • The primary plan picks up its coverage amount. Let’s say that’s $50.
  • Then, the secondary insurance plan picks up its part of the cost up to 100% — as long as the insurer covers the health care services.
  • You pay whatever the two plans didn’t cover.

That sounds great, right? Well, having two health plans also means that you’ll likely need to pay two premiums and deal with deductibles for two health plans. But, couples may choose to have two plans if they are both employer-sponsored.

When coordination of benefits is needed

There are various situations when two health insurers need to coordinate on medical claims. You and your spouse may be eligible for two different policies from your jobs. Your spouse might be on Medicare and you have your own health plan. You might be under 26 and have your employer’s and parent’s insurance coverage.

Here is a list of situations and which plan would likely serve as the primary insurer and which ones would probably be secondary:

SituationWho’s primaryWho’s secondary
You’re married and both you and your spouse have separate health plansYour employerYour spouse’s employer
A child has dual coverage by married parentsWhichever parent has the first birthday in calendar yearParent with later birthday
A child has divorced parentsWhoever has custodyN/A
A child has own policy (from school or work) and still on parent’s policy until 26Child’s planParent’s plan
A child is married and on spouse’s policy and continues on parent’s policy until 26Child or child’s spouse’s planParent’s plan
A child under 26 is pregnant and on a parent’s planChild’s planN/A
Workers’ compensation and health insurance planWorkers’ compensationHealth plan
COBRA and other insuranceEmployer’s planCOBRA
Medicare and a private health insurance planMedicare if employer has 100 or fewer employees; private insurer if more than 100 employeesPrivate insurer is 100 or fewer employees; Medicare if more than 100 employees
Veterans Administration (VA) and a private health insurance planPrivate insurerN/A
Military coverage (TRICARE) and other health insuranceOther insurerTRICARE except if other plan is Medicaid
Medicaid and a health insurance planHealth insurance planMedicaid

Examples of coordination of benefits for dependents

Coordination of benefits can sometimes get complicated — especially if the healthcare plan is for a child or dependent. Here are just a few examples of how coordination of benefits works for dependents:

  • A child has dual coverage by married parents: In this case, the birthday rule will apply, which states that whichever parent has the first birthday in a calendar year is the one whose insurance plan is considered primary. It’s not who is oldest — it’s where the birthday (month and day) falls in the calendar year. If parents have the same birthday, the primary coverage will go to the plan that has covered a parent longer.
  • A child has divorced parents: The child is usually covered by the parent who has custody. If the child’s custodial parent remarried, the step-parent’s plan may provide secondary coverage for the child. The plan of the parent who doesn’t have custody usually pays last. If it’s joint custody, then the birthday rule usually applies. Additionally, a divorce decree may also influence which plan is primary. If the divorce states that one parent is financially responsible for the child’s healthcare expenses, that parent’s plan should be primary for the child and the other parent’s policy is secondary.
  • A child under 26 is pregnant and on a parent’s plan: The health insurance status would stay the same for the child who is under 26; the parent’s insurance serves as secondary. However, it works differently for newborns. Once the child is born, they will need to be covered by their parent – not their grandparent. 

What are the different types of coordination of benefits?

Coordination of benefits is not one size fits all — there are a few different types of COB coverages: 

  • Carve out: The amount your primary plan paid is deducted from how much your primary plan can pay. 
  • Non-duplication: If the primary health insurance plan paid an amount that is equal to or more than what the secondary plan would pay, then the secondary plan does not pay out at all. 
  • Traditional: Your health insurance plans combined can cover up to 100% of your medical expenses. 

You should discuss your best options and what your coordination of benefits offers with your benefits administrator or health insurance company. 

Frequently Asked Questions

Can you have two health insurance plans?

Yes, you can have more than one health plan.

Having two health plans may mean having to pay two premiums. However, two health plans may also help reduce out-of-pocket expenses when you need health care.

What is secondary insurance?

Secondary insurance is the health plan that pays second as part of the COB process.

The health plan that pays first and which one pays second depends on the type of plans and the situation. Check the table earlier on the page to see some of the scenarios.

How do I update my Medicare coordination of benefits?

There are a few different ways to update your Medicare coordination of benefits. For starters, reach out to your employer or union benefits administrator to update your benefits. If you still need help, try calling the benefits coordination hotline at 1-855-798-2627. 

Sources: “Coordination of Benefits.“Accessed June 2022.

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Nupur Gambhir
Managing Editor


Nupur Gambhir is a content editor and licensed life, health, and disability insurance expert. She has extensive experience bringing brands to life and has built award-nominated campaigns for travel and tech. Her insurance expertise has been featured in Bloomberg News, Forbes Advisor, CNET, Fortune, Slate, Real Simple, Lifehacker, The Financial Gym, and the end-of-life planning service.