Dual Coverage and Coordination of Benefits

Dual dental coverage occurs when a person is covered by two dental insurance plans simultaneously. This situation is quite common and happens in several scenarios that you might encounter in your practice.

The most typical situations where patients have dual coverage include:

• A patient who is covered by their own employer's dental plan and is also a dependent on their spouse's plan

• A child who is covered under both parents' separate dental insurance plans

• A person who has two benefit-eligible jobs, each providing dental coverage

• An individual with private dental insurance who also has coverage through Medicare or Medicaid

Patients typically choose dual coverage for one simple reason: to save money on dental care and maximize the benefits of their dental treatment plan.

Similarly, children of divorced or separated parents may keep coverage under both parents' plans to get the most from their benefits.

How Coordination of Benefits Works

When a patient has dual coverage, insurance companies use coordination of benefits (COB) to determine how the plans work together. This prevents overpayment while maximizing benefits.

With dual coverage:

• One plan is "primary" and pays first according to its normal benefits

• The second plan is "secondary" and may cover some remaining costs

• The total payment from both plans cannot exceed 100% of the allowed amount

Your primary insurance always pays first according to its regular benefit schedule. After the primary insurer processes the claim, the secondary insurance considers the remaining balance.

The Explanation of Benefits (EOB) plays a fundamental role in the COB process. After your primary insurer processes a claim, they send an EOB that outlines:

• Treatment received

• Amount charged by the dentist

• Amount covered by insurance

• Amount not covered and why

• Your financial responsibility

To initiate the coordination process, you must submit this EOB to your secondary insurance along with the claim. Without a primary EOB, secondary claims cannot be processed.

General Rules for Determining Primary and Secondary Insurance

When patients have coverage under multiple dental insurance plans, determining primary and secondary insurance is imperative for proper claims processing. These coordination of benefits (COB) rules will help you maximize patient benefits and maintain accurate billing.

Subscriber vs. Dependent Rule

The most fundamental rule in determining primary insurance is the subscriber versus dependent status. When a patient has coverage as both a subscriber (through their own employment) and as a dependent (through someone else's plan):

• The plan covering the patient as a subscriber/employee is always primary

• The plan covering the patient as a dependent is secondary

For example, suppose Michael has dental coverage through his employer and is also covered as a dependent on his spouse's plan. In that case, Michael's employer plan will be primary, and his spouse's plan will be secondary.

Length of Coverage Rule

When both plans cover a patient in the same capacity (such as two employer-based plans), the length of coverage becomes the deciding factor. The plan that has covered the patient longer is primary, and the newer plan is secondary

This rule typically applies when determining primary coverage isn't possible using other standard rules.

COBRA and Retiree Plans

When comparing active employee coverage against COBRA continuation coverage or retiree plans:

• Active employee coverage is always primary

• COBRA or retiree coverage is always secondary

For instance, if Michael has both Medicare and a retiree dental plan from his former employer and takes a part-time job with dental benefits, the new employer's plan would be primary despite being newer.

How to Determine Primary and Secondary Insurance for Children

When a child is covered under multiple dental insurance plans, specific rules apply that differ from adult coverage determination.

The Birthday Rule

The most common method for determining primary coverage is the "Birthday Rule." Under this guideline, the parent whose birthday (month and day only, not year) falls earlier in the calendar year provides the primary insurance for dependent children. For example, if one parent's birthday is March 15th and the other's is September 8th, the March birthday parent's plan is primary.

Court Orders and Custody Situations

Legal agreements override the Birthday Rule. If parents are divorced or legally separated, a court order specifying insurance responsibility precedes all other rules. Without a specific court order, the plan of the parent with custody generally provides primary coverage. The Birthday Rule may still apply in joint custody arrangements unless legally specified otherwise.

Step-parent or Guardian Coverage

In blended families, insurance coordination becomes more complex. When a custodial parent remarries:

• The custodial parent's plan remains primary

• The new spouse's (step-parent's) plan becomes secondary

• The non-custodial parent's plan fills any remaining coverage gaps

For example, Michael and Sarah are divorced with joint custody of their daughter Emma. Michael's birthday is in April, while Sarah's is in August. The divorce decree states explicitly that Sarah's plan provides primary coverage. In this case, despite the Birthday Rule pointing to Michael's plan, Sarah's insurance is primary because the court order takes precedence.

Common COB Methods Used by Insurers

Insurance companies use specific Coordination of Benefits (COB) methods to calculate benefits when a patient has dual coverage.

Traditional COB

The most common method is Traditional COB, where the patient can receive up to 100% of covered expenses from the combination of primary and secondary plans. Here's how it works:

1. The primary plan pays its normal benefit amount first

2. The secondary plan then considers the remaining balance

3. The secondary pays up to its normal benefit amount, not exceeding the total bill

This approach aims to provide maximum coverage without overpayment. For example, if a patient needs a $1,000 crown with 50% coverage from each plan, the primary would pay $500, and the secondary would cover the remaining $500, leaving the patient with no out-of-pocket cost.

Maintenance of Benefits (MOB)

With the Maintenance of Benefits method, the secondary insurer reduces covered charges by the amount paid by the primary plan, then applies the secondary plan's deductible and coinsurance to the remainder.

This results in lower secondary payments compared to traditional COB. Using the crown example from above, if the primary plan pays $500, the secondary would apply its 50% coverage to the remaining $500. Still, it might only pay $250 after applying deductibles, leaving the patient responsible for $250.

Carve-Out Method

The Carve-Out Method is a common approach used by secondary insurance carriers to limit their payment responsibility based on what they would have paid as the primary plan. It involves a few key steps:

• Calculate what the secondary plan would have paid if it were the primary.

• Subtract the amount already paid by the actual primary plan.

• Pay the remaining difference, if any.

For example, if both the primary and secondary plans would each allow $500 for a crown when acting as the primary payer, and the primary has already covered the full $500, the secondary owes nothing. But if the secondary plan would have paid $600 as primary, it would contribute the $100 difference.

The Carve-Out Method doesn’t always guarantee full coverage for patients. Instead of supplementing the remaining balance up to the provider’s charge, the secondary plan simply makes up the gap between its allowed amount and what the primary already paid, often resulting in a remaining patient balance.

It’s helpful to communicate this to patients upfront, particularly when they assume having two plans means no out-of-pocket costs. Understanding the carve-out calculation can help your front office team avoid surprises and proactively manage expectations.

Non-Duplication of Benefits

With Non-Duplication of Benefits, the secondary plan pays nothing if the primary plan's payment equals or exceeds what the secondary plan would have paid as primary. This method is often used in self-funded dental plans to reduce costs.

In our crown example, if both plans cover crowns at 50%, the secondary plan would pay nothing since the primary's $500 payment equals what the secondary would have paid as primary.

Many secondary plans include a non-duplication of benefits clause. If the primary plan pays as much or more than what the secondary plan would have paid as primary, the secondary plan pays nothing.

Always verify which COB method applies to each of your patients' plans before processing claims. Most insurers will specify their COB approach in their provider manuals or benefit documentation, so keep these references handy for your billing team.

How to Handle Claims with Dual Coverage

When handled properly, dual coverage and effective dental payment programs can provide more comprehensive coverage for patients and maximize reimbursement for your practice.

Always Bill Full Fee to Both Plans

When a patient has coverage under two dental plans, bill the full fee to both insurance companies. Many dental offices mistakenly bill only the remaining balance to the secondary insurance, which often results in reduced reimbursement.

Submit the full fee to both the primary and secondary carriers. Each insurance company will calculate benefits based on the complete treatment cost rather than a partial amount. Insurance companies will coordinate payments between themselves; your job is to provide complete and accurate information.

Submit to Primary First, Then to Secondary with EOB Attached

The order of submission matters tremendously when handling dual coverage. Follow these steps:

1. Determine which plan is primary (typically the patient's own plan if they're the subscriber, or following the "birthday rule" for dependents)

2. Submit the claim to the primary insurance first

3. Wait for the primary to process and provide an Explanation of Benefits (EOB)

4. Submit the same claim to the secondary insurance with the primary's EOB attached

This sequencing is important because the secondary insurance needs to see what the primary has already paid to coordinate benefits properly. Without the primary EOB, the secondary carrier will likely deny or delay the claim.

How to Prevent Denials and Delays

To simplify dual coverage claims, verify both insurance plans before treatment and confirm which is primary. You should also understand each plan's coordination of benefits provisions (some have non-duplication clauses), and submit the secondary claim promptly after receiving the primary EOB.

Follow up consistently on outstanding claims, keep patients informed about their coverage and potential out-of-pocket costs, and train your team on coordination of benefits rules and any state-specific regulations.

Keep in mind that thorough documentation protects you against claim denials and payment delays. When dealing with dual coverage, confirm that your files include:

• Complete information on both insurance plans

• Clear documentation of which plan is primary versus secondary

• Copies of all EOBs from both carriers

• Records of all communication with insurance companies

Tip: Train front desk staff to explain dual coverage basics clearly, so patients understand what to expect from their insurance and avoid surprise bills.

Following these guidelines and utilizing AI dental insurance verification tools can reduce billing headaches and improve your claims success rate.

Special Considerations

There are a few additional instances and factors to consider when dealing with primary and secondary insurance billing. 

Watch for Non-Duplication Clauses

Non-duplication of benefits clauses can surprise patients. These provisions limit what secondary insurers will pay. 

If a patient's primary plan covers 50% of a procedure and their secondary plan has a non-duplication clause with 80% coverage, the secondary plan won't pay the full remaining 50%. Instead, they'll only pay the difference between their normal benefit (80%) and what the primary plan paid (50%), resulting in 30% additional coverage. 

These clauses can significantly impact patient out-of-pocket costs, so verify these details when estimating patient responsibilities.

Be Aware of Self-Funded Plans and ERISA Regulations

Many dental plans fall under ERISA regulation as self-funded plans. These plans claim exemption from many state insurance laws, creating confusion about which regulations apply.

Standard state insurance rules may not apply when processing claims for patients with ERISA-governed plans. This affects everything from payment timelines to the coordination of benefits processes. Always verify if a plan is ERISA-regulated when determining how to handle dual coverage situations, as this can dramatically change how benefits are coordinated and claims are processed.

State-Specific COB Rules May Apply

Different states maintain their regulations governing the coordination of benefits. Key areas where states differ include assignment of benefits laws, prompt payment requirements, non-covered services provisions, and prior authorization rules.

Multi-state practices face particular challenges navigating these differences. Stay current with your state's specific requirements, as non-compliance can lead to claim denials, payment delays, and potential legal issues.

If your dental office operates across state lines or has complex coordination cases, consider developing standard operating procedures and consulting with a healthcare attorney.

Keep Your Practice Running Smoothly

Dealing with dual dental insurance doesn’t have to be a headache. Once you understand how to tell which plan is primary and which is secondary, the whole billing process becomes much smoother. It helps your team avoid delays, get claims paid faster, and keeps patients happy by minimizing surprise costs.

However, managing this stuff takes time, attention to detail, and a solid team. If your practice is short-staffed or needs extra help, Teero can make a big difference. Teero connects dental offices with reliable hygienists so you’re always covered, even on your busiest days.

Need help keeping your practice running smoothly? Call us and get the support you need to stay focused on patient care.