What is the purpose of the AT modifier?

• A. It narrows CMS coverage to acute or chronic subluxation and must be used on claims for active/corrective treatment
• B. It indicates anesthesia
• C. It broadens coverage to all conditions
• D. It is optional and has no effect on coverage

Answer: (A)

The AT modifier signals Active Treatment in chiropractic billing, indicating that the services billed are aimed at actively correcting or improving a subluxation rather than just providing passive or maintenance care. This designation guides CMS that the care is specifically active, corrective treatment for subluxation, which is the condition CMS limits coverage for. Because coverage is narrowed to subluxation-related active care, the AT modifier must be used on claims for active or corrective treatment to ensure the services are evaluated under that allowable scope. It isn’t about anesthesia, it doesn’t broaden coverage to all conditions, and it isn’t optional when active treatment is being provided.