Coordination of Benefits by State: What Providers Need to Know
Coordination of benefits by state matters because every state sets its own rules. Coordination of benefits is the set of rules that decides which health plan pays first when a patient has more than one. This guide shows therapists, psychiatrists, and their billing staff how the order is set, what to verify, and how the household's plan choices change who pays first.
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Last reviewed: 10/27/26. Sources are listed at the bottom of the page.
What coordination of benefits means
Two plans, one visit, one order of payment.
Coordination of benefits (COB) is how health plans decide which one pays first and which one pays second when a patient is covered twice. The goal is simple: the plans together should not pay more than the allowed amount for the visit. The National Association of Insurance Commissioners (NAIC) publishes the model rule most states and plans follow, called Model 120, the Coordination of Benefits Model Regulation.
For a mental health practice, coordination of benefits decides where the first claim goes. Send it to the wrong plan and you get a denial, a delay, or a payment you have to return. Send it to the right plan and the second plan can pick up part of the balance. The step-by-step billing work for the second plan is covered in our guide to secondary claims, and the plain definition lives in the billing terms glossary.
MCM South works only with psychotherapists and psychiatrists, so the examples here are mental and behavioral health visits: psychotherapy, E/M visits with add-on psychotherapy, and telehealth sessions.
Who pays first: the standard order
The rules come from the plan documents and state law, not from the patient's preference.
The order of benefit determination follows a ladder. The first rule that applies sets the order. Under the NAIC model, the usual steps are:
- A plan with no coordination of benefits provision pays first.
- The plan that covers the person as an employee or subscriber pays before the plan that covers the person as a dependent.
- For a child covered by both parents, the plan of the parent whose birthday falls earlier in the calendar year pays first. This is the birthday rule.
- For separated or divorced parents, a court order or the plan's own rules can override the birthday rule.
- A plan covering a person as an active employee pays before a plan covering the same person as a retiree or laid-off employee.
- COBRA continuation coverage pays after the plan the person is covered under another way.
- If nothing else settles it, the plan that has covered the person longer pays first.
States adopt the model with changes, and self-funded employer plans may follow federal rules instead of state law. The rule varies by state and by plan, so confirm the order with the plan itself. Our state billing guides list state-specific contacts.
Primary and secondary insurance: submit in this order
Always bill the primary insurance first. Bill the secondary insurance only after the primary insurance has answered the claim, and send the primary’s response with it.
The rule in one line: primary first, then secondary after the primary’s response.
The secondary insurance needs to see what the primary paid, adjusted or denied. A claim sent to the secondary with no primary response is usually denied or held.
What it is
Definition: the plan that pays first. It processes the claim as if no other coverage existed, using its own allowed amount, copay, deductible and coinsurance.
Process
- Verify eligibility and record which plan is primary. See insurance verification.
- Submit the claim to the primary within its filing limit. Keep the clearinghouse acceptance report as proof of submission.
- Wait for the primary’s response: the electronic remittance advice (ERA) or the paper explanation of benefits (EOB).
- Post the payment, the adjustment and the patient responsibility from that response.
What it is
Definition: the plan that pays second. It looks at what the primary already paid and may cover some or all of the remaining patient responsibility, under its own rules.
Process
- Confirm the primary has finished processing, with a payment or a denial in hand.
- Submit the secondary claim with the primary’s payment and adjustment details attached or entered on the claim.
- Include the primary’s ERA or EOB if the secondary asks for it, and check its filing limit, which may run from the primary’s response date.
- Post the secondary payment. Bill the patient only what is left after both plans. See secondary claims.
Proof of submission versus the primary’s response
Proof of submission shows you filed on time. The clearinghouse acceptance report and the payer’s claim acknowledgment are examples. It protects you if the primary is slow or loses the claim. It does not replace the primary’s response. To bill the secondary, you normally need the primary’s ERA or EOB. If the primary never responds, keep your proof of submission, follow up with the payer, and ask the secondary how it handles a late primary response. Rules vary by plan.
Examples
The dollar amounts below are made-up numbers to show the flow. They are not payer rates.
Example 1: primary pays, secondary covers the copay
| Billed amount | $180 |
| Primary allowed amount | $130 |
| Patient copay on primary | $25 |
| Primary pays | $105 |
| Contract adjustment (in network) | $50 |
| Sent to secondary with the primary’s ERA | $25 remaining |
The secondary may pay up to the $25, depending on its own allowed amount and benefits. The patient owes only what is still unpaid after the secondary responds.
Example 2: primary denies for coverage
- You bill the plan on the card. It denies because coverage ended before the date of service.
- You ask the patient for current coverage and verify it.
- You bill the plan that is now correct as primary, and keep the first denial on file.
- If a second plan is active, you bill it as secondary after the primary responds.
The order follows the rules in the next sections, not the order of the cards in the patient’s wallet.
Example 3: a child on two parents’ plans
Parent A’s birthday is March 5. Parent B’s is August 20. Under the birthday rule, Parent A’s plan is primary because March comes earlier in the year. Bill Parent A’s plan first, then Parent B’s plan as secondary. If the parents are separated, a court order decides.
Example 4: a timeline
- Session date: verify both plans.
- Submit to the primary and save the acceptance report.
- Receive the primary ERA or EOB and post it.
- Submit to the secondary with that response.
- Post the secondary payment and bill the patient any balance.
This section is billing guidance for therapists and psychiatrists, not legal advice. Each plan sets its own filing limits and attachment rules. See our in-network vs out-of-network guide for how network status changes what a plan pays, and the billing terms glossary for terms like ERA, EOB and allowed amount. MCM South bills primary and secondary claims for psychotherapists and psychiatrists: secondary claims billing.
Who pays first? Try the checker
Pick the patient’s situation to see the usual order. It is a starting point, not a payer decision. Always verify with the plan.
Select a situation above.
Coordination of benefits by state
Each state adopts the NAIC model its own way. Choose a state to see the rule for each of the ten states MCM South currently serves.
Coordination of benefits in Georgia
Georgia’s group rule is Ga. Comp. R. & Regs. 120-2-48. It uses the standard ladder: employee plan before dependent plan, the birthday rule for children, and the plan with longer coverage as the tiebreaker. The rule does not mention COBRA, and state Medicaid is excluded from the definition of a plan.
See the Georgia insurance contact guide.
Coordination of benefits in Massachusetts
Massachusetts follows 211 CMR 38.00. COBRA or state continuation coverage is expressly secondary. Personal injury protection (PIP) auto coverage is primary for the first $2,000 after an auto accident, and the state Medicaid plan is excluded from the definition of a plan.
Coordination of benefits in Connecticut
Connecticut’s group rules are Regs. Conn. State Agencies 38a-480-1 to 38a-480-7 (text copy on Justia). The Office of the Healthcare Advocate says the employer plan pays first and COBRA is secondary. A 2021 Insurance Department notice says the statute controls over the regulation on the Medicare carve-out.
See the Connecticut insurance contact guide.
Coordination of benefits in Texas
Texas uses 28 Tex. Admin. Code §§3.3501-3.3510, adopted in a 2014 Texas Department of Insurance order (section 3.3507 text copy). It covers individual as well as group plans, makes COBRA secondary, and requires a secondary carrier to give information within 7 days of a request.
See the Texas insurance contact guide.
Coordination of benefits in Florida
Florida has a statute, not a stand-alone regulation: Fla. Stat. 627.4235. It sets the employee-before-dependent and birthday rules, makes COBRA secondary, and reverses the order for Medicare in some cases.
See the Florida insurance contact guide.
Coordination of benefits in New York
New York’s rule is 11 NYCRR 52.23 (Regulation 62), available as a Cornell Legal Information Institute text copy. It uses the birthday rule and excludes a state Medicaid plan from the definition of a plan.
See the New York insurance contact guide.
Coordination of benefits in Colorado
Colorado’s group rule is 3 CCR 702-4, Regulation 4-6-2 (text copy on Cornell LII). COBRA or state continuation coverage is expressly secondary, and a court decree controls the order for a child of separated parents.
See the Colorado insurance contact guide.
Coordination of benefits in Tennessee
Tennessee’s rule 0780-01-53 is one of the oldest of the ten, filed in 1986. It uses the birthday rule and excludes a state Medicaid plan from the definition of a plan.
See the Tennessee insurance contact guide.
Coordination of benefits in North Carolina
North Carolina uses 11 NCAC 12 .0514 for group coverage (text copy on Justia). A separate law, G.S. 58-51-115, bars an insurer from considering Medicaid eligibility when it decides coverage or payment.
Coordination of benefits in Illinois
Illinois uses 50 Ill. Adm. Code Part 2009. Continuation coverage is secondary to coverage as an active employee, and a plan with no COB provision cannot count other plans’ benefits.
See the Illinois insurance contact guide.
These are summaries of the rule text we read on 10/27/26. Where a link says text copy, we could not reach the official publisher’s page, so compare it with the official text. Self-funded employer plans may follow federal rules instead, and states amend rules, so confirm with the plan before you rely on a detail.
Why plan choices are a household financial decision
Patients do not pick which plan pays first, but they do pick which plans they carry.
A patient cannot tell you "make my spouse's plan primary" and have it count. The order comes from the rules above. What a household does choose, usually at open enrollment, is which plans to enroll in and who to cover on each. That choice changes the order.
Here is a common example. A couple has two employer plans. One spouse needs ongoing specialist care, such as cancer treatment. The household decides to keep that spouse on the plan with the strongest specialist network and lowest out-of-pocket maximum. Other family members are then covered on whichever plan costs less. Because the employee plan pays before the dependent plan, the order for each person follows from who is enrolled where.
For your practice this means the order of benefits can change on January 1, mid-year after a job change, or after a divorce. A patient you saw all last year with plan A as primary may now have plan B first. Ask at intake, and ask again every January. Our post on open enrollment changes for private practices walks through the yearly check. For the provider's view of the whole question, read secondary claims for mental health.
Do not advise patients which plan to choose. That is a financial and insurance decision for the household, and an insurance agent or benefits office can help.
Medicare and Medicaid are separate rules
Keep private-payer, Medicare, and Medicaid rules in separate boxes.
Private payers
The NAIC model rules above apply to group and individual health plans, as adopted by each state and written into each plan.
Medicare as secondary payer
Medicare is not always first. Under Medicare Secondary Payer rules, a group health plan pays first for an employee who is still working when the employer has 20 or more employees. For a person on Medicare because of age who has COBRA, Medicare generally pays first. The CMS Coordination of Benefits and Recovery overview lists the current thresholds, including those for disability and end-stage renal disease. We last read that page on 10/27/26.
Medicaid and state rules
Medicaid is generally the payer of last resort, and each state Medicaid program publishes its own billing instructions. Check the state Medicaid provider manual before billing Medicaid as second. Our Medicaid managed care guide covers how plan contracts change the process.
What to verify at intake and every January
Five checks that prevent most coordination of benefits denials.
- Ask whether the patient has any other health coverage, including a spouse's or a parent's plan.
- Copy both insurance cards, front and back, and record the subscriber and date of birth for each plan.
- Run an eligibility check on both plans. Our insurance verification and eligibility checks service does this before the first visit.
- Call the primary plan if its record shows other coverage you did not expect. Plans often send the patient a COB questionnaire, and claims can pend until it is returned.
- Re-verify every January and any time the patient reports a job, marriage, birth, or divorce.
When both plans are in order, bill the primary first, then send the second claim with the primary plan's remittance attached. The secondary claims billing service from MCM South handles that follow-up for psychotherapists and psychiatrists.
Common coordination of benefits problems and fixes
Most denials trace back to one stale record.
- Primary denies for "other insurance on file." The plan thinks another payer is first. Verify the order with the patient, then call the plan to update its record.
- Secondary denies with no primary payment. Attach the primary remittance. Read the codes with our guide to CARC and RARC codes.
- Wrong plan billed first. Submit a corrected claim or follow the plan's process, and watch the filing deadline.
- Overpayment request. A plan found out later it should have been second. Ask for the request in writing and review the refund steps with your compliance contact.
Clean order-of-benefit records also raise your clean claim rate.
What to do Monday morning
Start small and fix the records first.
- Pull a list of patients with two plans.
- Check that both plans are on file and the order is right.
- Call one payer to confirm what it has on record.
- Add the other-insurance question to your intake form.
- Review the practices we serve page if you want help with this work.
Frequently asked questions
What is coordination of benefits?
Coordination of benefits is the set of rules that decides which health plan pays first when a patient is covered by more than one plan, so the total paid does not exceed the allowed amount.
Can a patient choose which insurance is primary?
No. The order follows plan rules, state law, and federal rules such as Medicare Secondary Payer. A household can choose which plans to carry and who is covered on each, and that choice changes the order.
How does the birthday rule work?
For a child covered by both parents, the plan of the parent whose birthday falls earlier in the calendar year usually pays first. A court order for separated parents can change this.
How often should we re-verify a patient's coverage?
At intake, every January, and whenever the patient reports a job change, marriage, birth, or divorce.
Does Medicare always pay first?
No. Medicare can be secondary when a group health plan should pay first, such as for a working employee at an employer with 20 or more employees. Check the CMS page for current thresholds.
Do coordination of benefits rules differ by state?
Yes. Each state adopts the NAIC model its own way, and self-funded employer plans may follow federal rules instead. Check the state rule and the plan document for each patient.
Get help with coordination of benefits
MCM South bills for psychotherapists and psychiatrists in ten currently served states: GA, MA, CT, TX, FL, NY, CO, TN, NC, and IL.
Sources checked (10/27/26)
- NAIC Model 120, Coordination of Benefits Model Regulation
- CMS Medicare Coordination of Benefits and Recovery overview
This page is operational guidance for billing, not legal advice. Confirm rules with the plan and your compliance contact.