For mental health providers in the United States, mastering insurance billing is already a challenge but secondary insurance billing can feel like navigating a minefield. Despite following all the right steps, many behavioral health practices still experience delayed payments, denials, or complete write-offs when billing secondary insurers.

So why does secondary billing fail so often, and more importantly, how can you fix it?

Here are some reasons and how to fix them

Incorrect Coordination of Benefits (COB)

Coordination of Benefits (COB) determines which payer is primary and which is secondary.
If COB information is missing or wrong even slightly, the secondary claim will automatically be denied.

How to Fix It:

• Always verify COB details directly with both the patient and the insurance company before providing services.
• Request a recent COB update from the insurance if there’s any doubt, especially with Medicare and Medicaid patients.

Incomplete Primary Explanation of Benefits (EOB)

Secondary payers require the primary EOB to process a claim.
If the EOB is missing, incomplete, or doesn’t match what’s billed, the secondary insurer will not pay.

How to Fix It:

• Attach a complete, legible EOB every time you submit to the secondary insurance.
• If submitting electronically, ensure your billing software transmits the primary EOB properly using electronic attachments (like 837 and 835 files).

Timely Filing Limits

Each secondary insurer has its own timely filing window some as short as 60–90 days after the primary payment.
If you miss this window, the claim is dead on arrival.

How to Fix It:

• Track dates carefully: know when the primary paid and act immediately.
• Set up billing system alerts for secondary billing deadlines.

Inconsistent Patient Responsibility

Secondary insurers will deny claims if patient responsibility (copays, coinsurance, deductibles) is miscalculated.
This is especially common with mental health billing because behavioral benefits often have different structures than medical benefits.

How to Fix It:

• Double-check copay, coinsurance, and deductible amounts listed on the primary EOB before billing the secondary.
• Watch for carve-outs and mental health parity rules that affect mental health billing differently.

Manual Errors in Claim Submission

Human error is still a major reason secondary claims fail.
Incorrect CPT codes, mismatched patient demographics, or even minor typos can cause denials.

How to Fix It:

• Use specialized mental health billing software when possible.
• Train billing staff to double-review secondary submissions before sending them.
• Consider working with a billing partner that has expertise specifically in mental health billing.

Lack of Specialized Knowledge in Behavioral Health Billing

Secondary billing isn’t just about technical steps mental health claims have nuances that general medical billing teams often miss.
From session limits to authorization requirements, mental health has a different set of billing rules.

How to Fix It:

• Make sure your billing team understands the mental health codes (like 90791, 90834, 90837) and payer-specific mental health policies.
• Stay updated with each insurer’s behavioral health coverage rules (especially BCBS, Aetna, UnitedHealthcare, and Medicaid plans).

Be Proactive

Secondary insurance billing doesn’t have to be a guessing game.
By tightening your processes, staying aware of behavioral health-specific rules, and investing in specialized support, your practice can maximize reimbursements and avoid unnecessary write-offs.

If you’re struggling with secondary billing for mental health services, consider partnering with a billing team that knows the mental health landscape inside and out.

If you would like expert guidance or help contact us @ info@providerscentralhub.com or call us at 516 366-4144