Box 13: Insured signature, assignment of benefits
By Dr. Daniel Turner, DC · Reviewed September 2, 2026
What goes in Box 13 of the CMS-1500?
The insured’s authorization directing the payer to send payment to the provider rather than to the patient, again typically SIGNATURE ON FILE backed by a signed assignment.
What does Box 13 mean for chiropractic billing?
This box is the difference between the payer paying you and the payer mailing your money to the patient. Out of network practices that skip assignment discover the consequence on the remittance, as code 100, payment sent to the patient.
The mistakes that turn this box into denials
- ✗No assignment captured for out of network patients
- ✗Assuming Box 27 alone controls where payment goes
The denials this box causes
- →PR-100 / CO-100 · see the full fix in the denial library
How Cervica fills Box 13
Cervica generates the CMS-1500 and its electronic 837P equivalent from the chart and the payer's own rules: identifiers from the verified insurance record, modifiers and codes per payer, and pre submission scrubbing that flags exactly the mistakes listed above before a claim leaves the building.
General information for billing teams, not billing advice for any individual claim. The NUCC's 1500 Claim Form instructions and each payer's companion guides control.