ABA Therapy denial code (Updated for 2026)

Common Causes for B13

Denials with code B13 typically happen for the following specific reasons:

• The claim was submitted to the secondary payer as the primary payer without first obtaining a determination from the actual primary insurance carrier.
• The Coordination of Benefits (COB) information on file with the insurance carrier is outdated, or the patient's family has not updated their primary insurance status with the payer.
• The primary insurance carrier's Explanation of Benefits (EOB) or Electronic Remittance Advice (ERA) was missing, incomplete, or not properly attached to the secondary claim submission.
• The secondary claim failed to include necessary coordination details, such as primary payer paid amounts, allowed amounts, and standard adjustment codes (CARCs/RARCs).

How to Prevent B13 Denials

To avoid receiving this denial in the future, implement these specific checks:

• Perform comprehensive insurance eligibility verification prior to the initiation of ABA therapy to identify all active coverages and determine the primary payer using the NAIC Birthday Rule or other COB guidelines.
• Require families of dual-covered patients to contact their insurance providers directly to update and confirm their coordination of benefits details prior to billing.
• Implement an automated billing workflow that ensures secondary claims are only generated and submitted after the primary payer's ERA has been received and parsed.
• Ensure that secondary billing templates or EDI 837 claim files accurately transmit primary payment details, including Loop 2320 (Other Subscriber Information) and Loop 2330 (Other Payer) data.

Appeal Letter Template for B13

If you believe this claim was denied incorrectly, you can use the following template to submit an appeal.

[Your Practice Header]
[Date]

[Payer Name]
[Appeals Department Address]

RE: Appeal for Claim [Claim Number]
Patient: [Patient Name]
ID: [Patient ID]
Date of Service: [Date]
Denial Code: B13 - ABA Therapy denial code

Dear Appeals Department,

I am writing to appeal the denial of the above-referenced claim, which was denied with code B13: "ABA Therapy denial code".

We are appealing the denial of claim [Claim Number] under denial code B13. The patient, [Patient Name], is covered under dual health plans, and the coordination of benefits has been properly established in accordance with NAIC guidelines. The primary payer, [Primary Payer Name], has already processed this claim, and we have attached the corresponding Explanation of Benefits (EOB) showing their payment of [Primary Paid Amount] and the remaining patient responsibility. As the secondary payer, [Secondary Payer Name] is responsible for processing the remaining coinsurance, copayment, or deductible up to the allowed limit of the policy. Please reprocess this claim immediately with the attached primary EOB to issue the correct secondary reimbursement.

Attached please find:
1. A copy of the original claim.
2. The relevant medical records supporting the service.
3. [Any other supporting documents].

We respectfully request that you reprocess this claim for payment.

Sincerely,

[Your Name]
[Title]
[Practice Name]