Who Pays First? Understanding Coordination of Benefits
If you have ever heard someone say, “I have two insurance plans, so why is this still a problem?” they are probably dealing with coordination of benefits.
This is one of the most common areas of confusion in health coverage. It comes up when a person is covered under more than one plan, such as a spouse’s plan and their own employer plan, a parent’s plan and another parent’s plan, or Medicare plus employer coverage. Washington rules allow health plans to coordinate benefits so the plans can determine which one pays first and which one may pay after that. The goal is to prevent duplicate payment beyond the covered expense, not to reduce legitimate coverage unfairly.
For employers, this matters because employees often bring these questions to HR or their benefits contact first. A clear explanation can help reduce frustration, avoid claim delays, and point people in the right direction before a billing issue becomes a much bigger problem.
What is coordination of benefits?
Coordination of benefits, often called COB, is the process used when a person has health coverage under more than one plan. One plan is designated the primary plan, which pays first according to its normal terms. The other plan is the secondary plan, which may then pay some of the remaining eligible amount, depending on its own rules and the details of the claim. Washington’s coordination rules state that the primary plan pays as if the other plan does not exist.
This does not usually mean the person gets reimbursed twice. In general, combined payments are not supposed to exceed the allowable covered expense.
Why this gets confusing so often
People often assume the plan they like best, the plan they use most, or the plan with the lower deductible should pay first. That is not how COB works.
The order is usually determined by plan rules and, in Washington, by coordination standards built into state regulation for many health plans. In some situations, federal rules also apply, especially when Medicare is involved.
That means the answer to “Who pays first?” depends on the type of coverage involved.
Common situations where COB applies
Coordination of benefits commonly comes up when someone has:
- Coverage through their own employer and also as a dependent on a spouse’s plan
- Coverage for a child under both parents’ plans
- Employer coverage plus Medicare
- Retiree coverage plus Medicare
- COBRA or state continuation coverage plus another active plan
- Private coverage plus Apple Health or Medicaid
Washington consumers can have more than one form of coverage, but the plans still need to follow an order of payment process.
Who usually pays first?
Here are a few of the most common COB rules people ask about.
If you are covered under your own employer plan and also under your spouse’s plan
In many cases, the plan covering you as the employee is primary, while the plan covering you as a dependent is secondary. Washington’s rules reflect that coverage as an active employee generally pays before coverage tied to retiree or laid-off status, and standard COB ordering generally treats direct coverage differently from dependent coverage.
If a child is covered under both parents’ plans
Washington uses the well-known birthday rule for many situations involving dependent children whose parents are married or living together. The parent whose birthday falls earlier in the calendar year has the primary plan for the child. If both parents have the same birthday, the plan that has covered that parent longer is primary.
This rule is about the month and day, not who is older.
If the child’s parents are divorced, separated, or not living together
Washington’s COB rules provide a more detailed order here. Typically, if there is a court decree assigning responsibility for the child’s health care coverage or expenses, that order can control once the plan has actual knowledge of it. If there is no such decree, the order generally moves from the custodial parent’s plan first, then the custodial parent’s spouse’s plan, then the noncustodial parent’s plan, and then the noncustodial parent’s spouse’s plan. For exact rules, please check your policy.
If someone has active employee coverage and COBRA
Washington’s COB rules state that the plan covering the person as an employee, member, subscriber, retiree, or dependent under that plan is primary, while COBRA or other continuation coverage is secondary in that comparison.
If someone has active employer coverage and retiree coverage
Washington’s rules say active employee coverage is generally primary over coverage based on retiree or laid-off status.
If Medicare is involved
This is where people can get especially confused because federal Medicare Secondary Payer rules may control the result. Medicare explains that in some situations the group health plan pays first and Medicare pays second, while in others Medicare pays first. For example, Medicare generally pays first with retiree coverage, but a group health plan may pay first in certain active employment situations depending on employer size and the reason for Medicare eligibility. Medicare also states that Medicaid never pays first for services Medicare covers.
Because Medicare coordination depends on specific facts, employees should avoid guessing and should check with their plan administrator or Medicare before assuming which card to use.
What employees should do when they have more than one plan
When a person has more than one health plan, accuracy matters. Claims can be delayed or denied simply because a carrier has outdated coverage information.
A good first step is to make sure every carrier has current information about all active coverage. Medicare specifically advises people to report changes in other health or drug coverage and to tell providers about those changes as well.
Employees should also:
- Keep copies of both ID cards
- Review explanations of benefits carefully
- Ask the provider’s billing office which plan they billed first
- Verify whether dependents are listed correctly
- Check whether a court order or custody arrangement affects dependent coverage
- Reach out before assuming a denied claim is final
What employers can do to help
This is one of those topics where a little communication can save a lot of time.
Employers can help by reminding employees to report other coverage changes during onboarding, open enrollment, qualifying life events, and Medicare transitions. It is also helpful to remind employees that HR or a broker can explain general process, but the insurance carrier and plan documents control how a specific claim is handled. That distinction is especially important with COB, since the order can depend on plan language, ate rules, and federal Medicare rules.
A short educational resource on COB can also reduce recurring questions around dependent coverage, divorce situations, dual coverage, and Medicare enrollment timing.
A few important reminders
Coordination of benefits does not mean every remaining balance will automatically be paid by the second plan.
It also does not mean employees should ignore EOBs, claim letters, or requests for other insurance information. In many cases, the issue is administrative and can be corrected, but it is much easier to fix early.
If a claim seems off, the best next step is usually to compare the EOB, verify which plan was billed first, and contact the carrier or plan administrator for a COB review.
Final takeaway
When more than one health plan is involved, “who pays first” is not a guess. It is determined by coordination of benefits rules.
For Washington employers, this is a useful topic to explain clearly because it affects real claims, real billing stress, and real employee questions. Helping employees understand the basics can make claims easier to resolve and can help them know when to ask for support before a small issue turns into a long one.
