Chiropractic Claims Submitted with Both the 'AT' and 'GA' Modifier to Reject

Published 05/29/2020

Effective for dates of service November 1, 2015, and forward, claims submitted for CPT codes 98940, 98941 and 98942, billed with both the AT and GA HCPCS modifiers on the same detail line, will reject. Rejected claims do not have appeal rights and should be resubmitted with appropriate corrections.

Description of the Codes Impacted

  • CPT 98940 Chiropractic manipulative treatment (CMT); spinal, one to two regions
  • CPT 98941 Chiropractic manipulative treatment (CMT); spinal, three to four regions
  • CPT 98942 Chiropractic manipulative treatment (CMT); spinal, five regions

Use of the AT and GA HCPCS Modifiers
Chiropractic claims submitted with HCPCS modifier AT indicate that the provider is supplying active/corrective treatment to treat acute or chronic subluxation. The AT HCPCS modifier may not be submitted with services that meet the definition of maintenance therapy.

Maintenance therapy includes services that seek to prevent disease and promote health, as well as prolong and enhance the quality of life, or maintain or prevent deterioration of a chronic condition. When further clinical improvement cannot reasonably be expected from continuous ongoing care, and the chiropractic treatment becomes supportive rather than corrective in nature, the treatment is then considered maintenance therapy.

If providing maintenance therapy, the provider may wish to obtain an Advance Beneficiary Notice (ABN) from the patient. When a validly executed ABN is on file (based on the expectation that Medicare will deny the service as not reasonable and necessary), the provider may apply the GA HCPCS modifier on the claim.

An ABN cannot be issued for services that are being billed with the AT HCPCS modifier. The AT HCPCS modifier serves as an indication that the chiropractor is providing an acute or chronic subluxation; it cannot be submitted when the services meet the definition of maintenance therapy. The AT and GA HCPCS modifiers cannot be used in combination on the same detail line for chiropractic services.


  • Chiropractic Coverage (PDF, 1.29 MB): Publication 100-02, Medicare Benefit Policy Manual, Chapter 15, section 30.5, 240, 240.1.2
  • Chiropractic Documentation Requirements (PDF, 1.5 MB): Publicaton 100-04, CMS Medicare Claims Processing Manual, Chapter 12, Section 220
  • Chiropractor by Definition (PDF, 207 KB): Publication 100-01, Medicare General Information, Eligibility & Entitlement, Chapter 5, section 70.6
  • For more information regarding the use of Advance Beneficiary Notices (ABNs), refer to the CMS Beneficiary Notices Initiative web page
  • MLN Matters® Number: SE1602 (PDF, 63 KB): Use of the AT modifier for Chiropractic Billing (New Information Along with Information in MM3449) 

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