Coordination of Benefits: A Billing Guide for Therapists

Key Takeaways

• Coordination of benefits (COB) decides which insurance plan pays first when a client has two.
• The primary plan pays first. The secondary plan may pick up some or all of what's left.
• For kids covered by both parents, the birthday rule usually decides which plan is primary.
• Medicare's place in line depends on things like employer size, whether the other coverage comes from a current job or a retiree plan, and why the client has Medicare.
• Medicaid pays last, after every other plan.
• Asking about dual coverage at intake saves you from a lot of denials later.

A new client hands you two insurance cards at intake. Great news for them. For you, it's the start of a small billing puzzle.

Which plan do you bill first? What happens to the second one? And why did that claim just come back "denied for coordination of benefits"?

Here's how coordination of benefits works for therapists: how to figure out which plan is primary, how to bill the secondary plan, and how to fix COB denials when they show up.

What Is Coordination of Benefits?

Coordination of benefits is the set of rules insurance companies use to decide which plan pays first when someone is covered by more than one. It also keeps the two plans from paying more than the service actually costs.

When a client has two plans:

• The primary plan pays first, based on its own benefits.
• The secondary plan looks at what the primary has already paid and may cover some or all of what's left, like a copay, coinsurance, or deductible.

Most states base their COB rules on the NAIC Coordination of Benefits Model Regulation, which was created to give plans a uniform order for paying claims. Medicare and Medicaid have their own federal rules on top of that.

When Do Clients Have Two Insurance Plans?

Clients don't always know they have two active plans, or that it matters for therapy. Here are the situations you'll see most:

• Their own job plus a spouse's or partner's plan. The most common one by far.
• A child covered by both parents. Very common in child and teen therapy, especially with separated or divorced parents.
• Two jobs with two plans. Less common, but it happens.
• Medicare plus an employer plan. Think clients 65 or older who are still working, or clients under 65 on Medicare because of a disability.
• Medicaid plus other coverage. Some clients qualify for Medicaid and also have a commercial or employer plan.

Primary vs. Secondary Insurance: The Coordination of Benefits Rules

For most commercial plans, the order of benefits follows the NAIC rules. Here's the simplified version:

1. Subscriber beats dependent. The plan where the client is the employee or policyholder will be considered primary over a plan where they're a dependent.
   • Example: Maria has her own plan through work and is also on her husband's plan. Her own plan is primary.
2. Active beats inactive. A plan from a current job usually comes before a retiree or COBRA plan.
3. Longer coverage wins. If the rules above don't settle it, the plan that's covered the person longer is usually primary.

Kids get their own set of rules.

The Birthday Rule

When a child is covered by both parents' plans and the parents are married or live together, the plan of the parent whose birthday comes first in the calendar year is primary. Only the month and day count, not the year.

• Example: Mom's birthday is March 15. Dad's is July 22. Mom's plan is primary, even if Dad is older.
• Same birthday? The plan that has covered the parent longer is primary.

Divorced or Separated Parents

This is where things get spicy. Under the NAIC model:

• A court decree comes first. If a divorce decree says one parent is responsible for the child's health coverage, that parent's plan is primary.
• If the decree says both parents are responsible, the birthday rule applies.
• If the decree gives the parents joint (shared) custody but doesn't say who's responsible for health coverage, the birthday rule applies too.
• If there's no court decree assigning responsibility for the child's health coverage at all, the order is:
  • Custodial parent's plan
  • Custodial parent's spouse's plan
  • Non-custodial parent's plan
  • Non-custodial parent's spouse's plan

In practice, ask parents if there's a court order about health insurance, and keep a copy of the relevant section in the billing record if there is.

One big caveat: states and individual plans can have their own variations. Always confirm the order with both plans before you bill.

Coordination of Benefits and Medicare

Medicare follows federal Medicare Secondary Payer rules instead of the NAIC model. According to Medicare.gov, here's how the most common therapy scenarios shake out:

There are more special cases, like workers' comp (for treatment tied to a work injury claim), no-fault or liability insurance (for treatment tied to an accident or injury), VA benefits, TRICARE, and COBRA, but these cover most of what you'll see.

Medicaid: The Payer of Last Resort

By law, Medicaid is the payer of last resort. That means almost any other coverage the client has, including Medicare and commercial plans, gets billed first.

What that looks like in your workflow:

1. Bill the other plan first.
2. Get the Explanation Of Benefits (EOB) or Electronic Remittance Advice (ERA).
3. Bill Medicaid as secondary, following your state's rules.

How much Medicaid pays after the primary depends on your state. If you don't know a client has other coverage and Medicaid pays first, expect the state to come back for that money later. Checking for other coverage at intake avoids the headache.

How to Bill Secondary Insurance

Once you know the order, here's the basic flow:

1. Bill the primary plan like you normally would.
2. Wait for the primary's EOB or ERA. Note what it allowed, what it paid, and what it assigned to the client (copay, coinsurance, deductible).
3. If Medicare is primary, check whether Medicare already sent the claim to the secondary plan automatically (a crossover). If it did, you don't need to submit the secondary claim yourself.
4. Bill the secondary plan with the primary's payment information included. Electronic claims carry this in the claim data. On paper claims, you'll fill in the other insurance fields and usually attach the primary EOB. Your clearinghouse or the payer's billing manual can tell you exactly what they need.
5. Wait for the secondary's EOB and figure out what, if anything, the client still owes.

If you want a refresher on reading remittances, our mental health billing guide covers the full billing cycle.

Behavioral Health Carve-Outs

Here's a therapist-specific wrinkle. Some health plans "carve out" mental health benefits to a separate company that manages behavioral health claims.

That means the name on the client's insurance card might not be who you actually bill for therapy. If a client has two plans and both carve out behavioral health, you could end up working with different companies than the ones on the cards.

The fix: when you verify benefits, ask each plan directly, "Who handles behavioral health benefits for this member, and where do claims go?"

A Quick Note on EAPs

Employee Assistance Programs (EAPs) aren't insurance, so they don't follow COB rules. Each EAP has its own process for referrals and for what happens when sessions run out. There's usually an approval process, and the client needs an authorization before using EAP sessions. The one hard rule: never bill the EAP and the insurance plan for the same session.

Coordination of Benefits Denials: What They Mean and How to Fix Them

A coordination of benefits denial means the plan you billed thinks something is off with the order of coverage. It's annoying, but usually fixable. Here are the most common causes:

The plan thinks another plan is primary. Call the plan, ask what other coverage they have on file, and get a reference number. If their info is wrong, the client may need to update it.

The plan is waiting on the client to answer a COB survey. Insurance companies regularly send members a survey asking whether they have other coverage, even members who only have one plan. If the client hasn't sent it back, the plan can deny claims until they do. You can spot this one by the denial wording (something like "COB requested from the insured") or by calling the plan. Tell the client their claims are being denied for this reason, ask them to contact their plan, then resubmit.

The secondary claim is missing the primary's payment info. Resubmit with the primary EOB or the right COB details included.

Both plans say the other one is primary. This is the hardest one to fix, because more often than not you can't sort it out yourself. It's up to the client and their plans. Get the client involved early: they may need to talk to both insurance companies, or even their employer, to settle the COB.

Don't let COB denials sit. Every plan has deadlines for resubmissions and appeals. For more on handling denials in general, see our guide to insurance claim denials.

What Does the Client Owe After Both Plans Pay?

Clients often assume two plans means they owe nothing. Sometimes that's true. Often it isn't.

How much the secondary plan pays depends on its own benefits and how it calculates coordination. Some secondary plans cover most or all of what the client owed after the primary. Others pay less, or nothing, if the primary already paid as much as the secondary would have.

Here's a simple hypothetical: the primary plan allows $150 for a session, pays $120, and leaves the client with $30 in coinsurance. Depending on the secondary plan, it might cover all $30, part of it, or none of it. The client owes whatever's left.

A good rule of thumb: the secondary plan processes the claim up to the primary plan's allowed amount. Exceptions exist with certain plans, but they're not common.

What to Ask at Intake to Catch Dual Coverage

The easiest COB problem to fix is the one you catch before the first claim. Add these to your intake paperwork:

• Do you have more than one health insurance plan?
• Are you covered by a spouse's, partner's, or parent's plan?
• Do you have Medicare or Medicaid?
• For minors: Are both parents' plans active? Is there a court order about who provides health insurance?
• Does your employer offer an EAP? If you plan to use it, have you gotten approval and authorization?

Then check again when things change:

• At the start of the year, after open enrollment
• Any time a client mentions a new job, job loss, marriage, divorce, or a new baby

Keeping track of two plans, two EOBs, and what each client owes is a lot of admin. Blueprint helps therapists spend less time on paperwork and more time with clients. See how Blueprint works.

Coordination of Benefits FAQ

What is coordination of benefits?

Coordination of benefits is how insurance companies decide which plan pays first when someone has more than one. It also keeps the plans from paying more than the service costs.

How do you determine which insurance is primary and secondary?

Usually, the plan where the client is the policyholder is primary, and the plan where they're a dependent is secondary. For kids, the birthday rule or a court order usually decides. Medicare and Medicaid have their own rules. When in doubt, call both plans.

What is the birthday rule in insurance?

For a child covered by both parents' plans, the plan of the parent whose birthday comes first in the calendar year is primary. Only the month and day count. A court order about health coverage can override it.

Does Medicare pay first or second?

It depends. For clients 65+ with coverage from a current job, the employer plan pays first if the employer has 20 or more employees. For clients under 65 on Medicare due to disability, the cutoff is 100 employees. Retiree plans and Medicaid pay after Medicare.

What does "denied for coordination of benefits" mean?

It means the plan thinks the order of coverage is wrong or its records are incomplete, often because the client's other coverage info is missing or out of date. Call the plan to find out what they have on file, fix it, and resubmit.

Can a client owe nothing if they have two insurance plans?

Sometimes, but not always. It depends on how the secondary plan calculates its payment. Let clients know at intake that they might still have a balance.

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