Let’s begin with the basics, but with a twist. Imagine two siblings showing up for a birthday party, both invited, but only one cake. COB is like negotiating who eats first and who gets leftovers. In the insurance world, it ensures that when a patient has more than one dental (or dental + medical) policy, benefit payments are coordinated so there's no overpaying, double-dipping, or confusion. The goal is that the patient gets optimal coverage (up to allowed limits), but no insurer winds up paying more than their fair share.

In the world of dentistry, COB means:

• You must figure out which plan is primary (pays first)

• Then submit the claim to that plan

• When the EOB (explanation of benefits) is returned, you may “pass the claim along” to the secondary plan with supporting documentation

• The secondary plan may pay remaining eligible amounts (depending on their rules)

• The total from both insurers + any patient payments should not exceed the actual submitted fee (or contracted fee). Duplication must be avoided.

Common “Rules of the Road” in COB: The Usual Suspects

Most dental offices are already familiar with these classic rules, but they remain essential guardrails:

• Subscriber vs Dependent
  If the patient is the subscriber (policyholder or employee), that policy is primary. Any policy where they’re merely a dependent is secondary.

• Active employment vs retiree / COBRA
  A policy through active employment is usually primary over a retiree or COBRA continuation plan.

• Dual employer plans
  If a person is covered under more than one employer-based plan, the one that has covered them the longest is often primary.

• Birthday rule (for children)
  When a child is covered under both parents’ policies, the parent whose birthday (month + day) comes first in the calendar year is primary.

• Divorce / court decree rules
  A court order or legal decree may override the birthday rule if it explicitly designates which parent’s plan is responsible for health/dental coverage.

• Medical vs Dental plans for oral/dento-surgical services
  Sometimes a patient’s medical insurer is primary (for trauma or medically necessary oral surgery) and the dental plan is secondary.

• Non-duplication / carve-out / maintenance of benefits
  Secondary plans often limit what they pay (or pay zero) depending on their “COB method.”

Even though these are well known, errors still creep in, such as treating the wrong plan as primary, or failing to forward EOBs. These are frequent causes of rejected claims or “COB denial codes.”

Less-Sung Complications & Advanced Considerations

These are the nuances, “gotchas,” and emerging trends that can make or break your success in maximizing dual coverage.

1. Self-Funded Plans & ERISA: The Wild West

Many employer dental plans are self-funded (the employer directly pays claims, rather than using an insurance carrier). These plans are governed by federal ERISA rules, not by state insurance laws. That means state-mandated COB laws may not apply.

Because of that, self-funded plans may include aggressive non-duplication clauses, carve-out policies, or unusual coordination formulas that you can’t predict without reading the actual plan documents. In fact, the ADA warns that not all dental plans (especially self-funded ones) follow state COB statutes.

Takeaway: when verifying benefits, ask whether the plan is self-funded and ask for its COB guidelines. Don’t assume “standard rules” will apply.

2. Non-Duplication / Carve-Out / Maintenance of Benefits / “Pay-After-Pay” Methods

Secondary plans don’t always simply “pay whatever remains.” Here are some of the less intuitive methods:

• Non-duplication (no pay): If the primary plan’s payment equals or exceeds what the secondary plan would have paid if it were primary, then the secondary plan pays nothing.

• Carve-out (reduction): The secondary plan calculates what it would have paid (if it were primary), then reduces that amount by what the primary already paid.

• Maintenance of benefits (MOB): The secondary applies its deductible and coinsurance on the remaining balance after the primary pays.

Because of these varieties, secondary payments sometimes surprise patients. The secondary might pay nothing or only partially cover. That’s why your team must be clear on each plan’s COB method, not just whether a secondary policy exists.

3. Timing & Timely-Filing Edge Cases

• Most secondary plans require you to submit the claim after the primary claim is processed (you include the EOB).

• If the primary insurer is slow, and the timely-filing deadline for the secondary is about to lapse, some practices (and some secondary insurers) allow “provisional” submissions to preserve the filing window. Then you amend or submit the EOB later.

• Certain federal or government dental plans may automatically coordinate benefits without requiring the EOB from the primary.

4. Write-Offs, Fee Submission Strategies & Overpayment Handling

• Submit your full fee (usual full charge) to all insurers, not a discounted or network rate. Apply write-offs only after all insurers pay (or deny).

• If combined payments exceed your submitted fee, you must notify the insurer(s) and potentially refund the excess.

• Follow state laws for write-offs and overpayment handling (such as California’s statutes).

5. Hidden Interplay with Medical Insurance

Sometimes the boundary between medical and dental becomes blurry, for example: trauma, oral surgical procedures, sleep apnea devices, TMJ, biopsy of oral lesions.

• The medical insurer may be primary (if procedure is medically necessary).

• The dental plan may be secondary.

• Some plans exclude coverage if another plan has already paid.

Always evaluate if a treatment might be billable to medical first. This can shift COB dynamics.

6. COB with Medicaid / Government Programs

• For Medicaid beneficiaries, other third-party resources must pay before Medicaid. Medicaid acts as a payer of last resort.

• For patients with Medicare and a supplemental retiree dental plan, the order is often: dependent policy (if present) → Medicare → retiree/dental. Rules vary by plan.

• Not all state Medicaid programs permit dental coordination or may limit secondary recovery from Medicaid.

Best Practices & “Secrets to the Trade” for Dental Offices

1. Make COB Verification Part of Intake

• Ask patients early if they have other dental or medical insurance.

• Collect subscriber names, policy numbers, dates, and COB provisions.

• Use software or services to detect overlapping coverage.

2. Request COB / Coordination Provisions Up Front

• Ask insurers about COB provisions, coordination methods, EOB requirements, and timely-filing deadlines.

• Document responses, including rep name, date, and time.

3. Flag & Handle Unusual / Aggressive COB Clauses

• Request the plan’s COB policy in writing.

• Compare stated COB method with actual payments.

• Appeal if necessary and track problem plans.

4. Smart Sequencing: Always File Primary First

5. Handle EOBs, Remittance Carefully

• Wait until all insurers have paid before write-offs.

• Reconcile totals with allowances.

• Handle overpayments properly.

6. Educate Patients Transparently

• Explain that dual plans don’t mean double coverage.

• Show estimates of primary and secondary coverage.

• Explain denials clearly.

7. Stay Sharp about Timely-Filing

• Track when primary EOB arrives.

• Monitor secondary filing deadlines.

• Use provisional submissions if permitted.

8. Analyze & Track Which Plans “Fight You” on COB

• Maintain a log of underpaying or denying plans.

• Share log with billing team.

• Use appeals more aggressively.

9. Test Alternative “What-If” Scenarios

• Run scenarios to compare outcomes if primary/secondary roles were reversed.

• Check if insurer COB methods changed.

• Use simulations to reveal opportunities or vulnerabilities.

A Sample Workflow: How It All Should Flow

• Patient intake → collect all dental/medical insurance information

• Benefits verification → call insurers, ask COB method, document responses

• Treatment planning / estimate → create a dual-insurance estimate

• Submit primary claim → with full charges

• Receive EOB → enter payments and adjustments

• Submit to secondary → attach primary EOB and forms

• Secondary remittance or denial → record payment or denial reasons

• Patient billing / write-off → reconcile insurance payments, bill patient, post write-offs

• Overpayment management → contact insurers before issuing refunds

• COB audit & reporting → track denials, payment times, and plan issues

Why Getting COB Right Matters

• Better patient loyalty: fewer surprises, more trust

• Incremental revenue gains: small amounts add up

• Competitive positioning: attract patients other offices refuse

• Data intelligence: leverage insights in negotiations

• Reduced denials and appeals: stronger documentation

Final Warnings & Reminders

• Always check plan documents.

• Be mindful of state COB statutes.

• Self-funded plans may not follow state guidelines.

• Never accept overpayment without reconciling.

• Secondary plans may pay little or nothing.

• Keep billing staff trained on evolving COB rules.

Benjamin Tuinei
Founder – Veritas Dental Resources, LLC
📞 888-808-4513
Services: PPO Fee Negotiators, PPO Fee Negotiating, Insurance Fee Negotiating, Insurance Credentialing, Insurance Verifications
Websites: www.VeritasDentalResources.com, www.VerusDental.com