The referral/authorization number is missing, invalid, or does not apply to the billed services (Updated for 2026)

Common Causes for 180

Denials with code 180 typically happen for the following specific reasons:

• Failure to obtain prior authorization or a referral from the primary care physician prior to rendering non-emergent services.
• Data entry errors where the authorization number was omitted or mistyped in Box 23 of the CMS-1500 form or Loop 2300 of the 837P electronic claim.
• The rendered CPT/HCPCS codes or dates of service do not match the specific codes, units, or date range approved in the original authorization.
• The authorization was secured under a different rendering provider, facility NPI, or tax ID than what was submitted on the claim.

How to Prevent 180 Denials

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

• Implement a robust insurance verification process to identify prior authorization and referral requirements prior to the patient's appointment.
• Establish an automated scrubbing system to ensure authorization numbers are correctly transcribed into Box 23 of the CMS-1500 claim form or Loop 2300 of the 837P transaction.
• Reconcile authorized CPT codes, approved units, and valid date ranges against the scheduled services before submitting the final claim.
• Provide ongoing training to scheduling and billing staff on updating authorizations when there are changes to the performing provider, facility, or clinical treatment plan.

Appeal Letter Template for 180

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: 180 - The referral/authorization number is missing, invalid, or does not apply to the billed services

Dear Appeals Department,

I am writing to appeal the denial of the above-referenced claim, which was denied with code 180: "The referral/authorization number is missing, invalid, or does not apply to the billed services".

Upon review of the denial for code 180, we have verified that a valid prior authorization was indeed active and obtained for these services. Prior authorization number [Insert Auth Number] was secured on [Insert Date] for CPT code(s) [Insert CPT Codes], covering the date of service [Insert Date of Service]. In accordance with CMS billing guidelines and payer-specific prior authorization rules, the rendered services fully align with the authorized clinical plan, the designated provider, and the approved timeframe. We have attached a copy of the original authorization approval letter alongside the clinical documentation to substantiate the medical necessity and proper authorization of the services. Therefore, we respectfully request that this denial be overturned and the claim be processed for payment immediately.

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]