Dental billing becomes more complex when patients have more than one insurance plan. While secondary insurance can reduce out-of-pocket costs and help practices collect faster, it often leads to delays if handled incorrectly.
Understanding how secondary billing works prevents payment errors, denied claims, and confusion for both dental teams and patients.
This guide explains how secondary insurance works and why accurate coordination of benefits is essential for smooth reimbursement.
What Secondary Insurance Means
Some patients are covered under two dental insurance policies usually through their employer and a spouse or parent.
In these cases, one plan is considered primary and the other secondary.
The primary plan pays first
The secondary plan may cover remaining balances
However, the secondary payer will not process a claim until the primary insurer has finalized theirs. This is why clean coordination matters.
How Coordination of Benefits (COB) Works
Coordination of benefits determines which plan pays first and how much the second plan is responsible for. Dental offices must have accurate COB information to avoid delays.
Common COB rules:
For adults with two plans, the patient’s own employer plan is usually primary
For children, the “birthday rule” is used the parent with the earlier birthday in the calendar year is primary
Court orders or legal agreements can override both rules
If COB is wrong, both plans may refuse payment until the information is corrected.
Steps to Bill Secondary Insurance Correctly
1. Submit the claim to the primary insurer
The primary insurance processes the claim and sends an Explanation of Benefits (EOB).
2. Post the primary payment
The practice updates the patient’s balance based on what the primary covered.
3. Submit the secondary claim
The secondary claim must include:
The primary EOB
Procedure codes
Remaining balance
Required documentation
If the EOB is missing, secondary carriers typically hold the claim or deny it automatically.
Why Secondary Billing Causes Delays
Even experienced dental teams can run into problems such as:
Wrong COB on file
Missing EOB attachments
Posting errors after primary payment
Sending claims to the wrong payer
Secondary plans that do not coordinate with the primary
Because both payers must communicate, one error can stop the entire claim from moving forward.
How Correct Secondary Billing Protects Revenue
When secondary billing is handled properly, practices collect more and patients owe less.
It improves:
Patient satisfaction
Collection rates
Insurance reimbursement accuracy
For busy teams, outsourcing billing ensures that COB, posting, and secondary submissions are handled correctly without losing revenue in the process.
Secondary insurance can be a financial advantage for dental practices, but only when claims are submitted accurately.
With the right workflow and documentation, secondary payers help reduce balances, speed up payments, and support predictable cash flow.
Practices that struggle with secondary billing often benefit from a professional billing partner who manages COB, posting, and follow-up ensuring nothing gets stuck in A/R.
