A complete guide to chiropractic CPT codes 98940-98943, AT modifier rules, spinal region documentation, and Medicare’s highest improper payment rate for chiropractic care.
Chiropractic billing carries the highest improper payment rate in all of Medicare - 33.6%, according to CMS's own compliance data, with projected improper payments exceeding $178 million. That's not a coding-complexity problem; the code set itself is small. It's a documentation and modifier-precision problem, and it's costing chiropractic practices real revenue every month.
The Core CMT Code Family: 98940–98943
Chiropractic Manipulative Treatment (CMT) is billed using four CPT codes, differentiated by one factor only: the number of spinal regions treated, not the number of individual adjustments performed.
- 98940 - CMT, 1–2 spinal regions
- 98941 - CMT, 3–4 spinal regions
- 98942 - CMT, 5 spinal regions (full spine)
- 98943 - CMT, extraspinal regions (extremities, head, ribs, abdomen)
CMS defines five spinal regions for billing purposes: cervical, thoracic, lumbar, sacral, and pelvic. A chiropractor performing three separate adjustments within the lumbar spine has still treated one region and bills 98940 - not a higher code reflecting adjustment count.
Documentation Has to Name the Regions, Not Just Count Them
Coding a higher region count than what's actually documented is upcoding and a direct audit trigger. The treatment note must specifically name which regions were treated and document subluxation findings for each - a note that simply states "1–2 regions" without naming them doesn't support the billed code on review.
The AT Modifier: Medicare's Single Biggest Chiropractic Denial Trigger
Medicare covers chiropractic manipulation only when it corrects a documented subluxation through active, corrective treatment - never maintenance care. The AT modifier signals that distinction, and it's required on every covered CMT claim.
Applying AT to maintenance therapy is not a minor coding error - CMS and multiple billing guides explicitly characterize it as a compliance violation, since it misrepresents non-covered maintenance care as active treatment eligible for reimbursement.
E/M Codes and Modifier 25 for Chiropractic Visits
Chiropractors can bill standard E/M codes (99202–99215) for initial evaluations and re-evaluations, separate from the manipulation itself. When an E/M service is billed on the same date as manipulation, modifier 25 must be appended to the E/M code to prevent an automatic bundling denial - a rule that trips up practices billing both services without the modifier.
Therapy and Modality Codes Often Billed Alongside CMT
Many chiropractic visits combine spinal manipulation with additional therapeutic services, billed under the same general timed-code framework used across musculoskeletal care broadly. This is where chiropractic billing overlaps directly with physical therapy CPT coding - codes like 97110 (therapeutic exercise), 97112 (neuromuscular re-education), and 97140 (manual therapy) follow the identical timed, 15-minute-unit billing logic regardless of whether a PT or a chiropractor performs them, including the same 8-minute rule for calculating billable units.
Common Denial Triggers Beyond the AT Modifier
- Region count mismatched to documentation - billing 98941 when notes only support 98940
- Missing or inappropriate AT modifier on active-treatment claims, or misapplied AT on maintenance visits
- No modifier 25 when billing an E/M code same-day as manipulation
- Vague subluxation documentation that doesn't tie findings to specific, named spinal regions
Where Musculoskeletal Monitoring Connects to Broader Care Coordination
Chiropractic patients managing chronic musculoskeletal conditions sometimes benefit from monitoring that extends beyond the office visit. Remote Therapeutic Monitoring, which tracks musculoskeletal therapy progress between visits rather than physiologic vitals, represents a distinct but related billing pathway some practices layer alongside standard MSK treatment for patients with more complex, ongoing needs.
How Circle Health Fits Into This Picture
Chiropractic CMT billing itself sits outside Circle Health's core services - CCM, RPM, PCM, BHI, and TCM are built around Medicare chronic care coordination, not spinal manipulation reimbursement. The genuine connection is narrower and worth stating honestly rather than overstating: chiropractic patients frequently present with the same chronic musculoskeletal and pain conditions that qualify for broader Medicare care management programs, and a chiropractor's clinical findings can be a relevant data point for a primary care provider coordinating that patient's overall chronic care picture.
For physician groups and health systems that also run musculoskeletal-focused Remote Therapeutic Monitoring alongside chiropractic or PT referrals, Circle Health's AI-powered platform and licensed care managers support that adjacent RTM billing and documentation - tracking therapy adherence and functional progress between visits - even though the chiropractic CMT codes themselves fall outside what Circle Health directly manages.
Conclusion
Chiropractic CPT coding is deceptively simple on paper - four core CMT codes, differentiated by region count - but the AT modifier and precise subluxation documentation are what separate compliant claims from the roughly one-in-three that Medicare's own data flags as improper. Getting region documentation, modifier application, and the active-versus-maintenance distinction right on every claim is what protects both revenue and audit exposure in a specialty where scrutiny is already unusually high.
Frequently Asked Questions
1. What's the difference between CPT 98940, 98941, and 98942?
These codes differ only by the number of spinal regions treated: 98940 covers 1–2 regions, 98941 covers 3–4 regions, and 98942 covers all 5 regions (full spine manipulation).
2. What does the AT modifier mean in chiropractic billing?
AT stands for Active Treatment. Medicare requires it on covered CMT claims to indicate the manipulation is corrective, active care - not maintenance therapy, which Medicare does not cover.
3. Can a chiropractor bill an E/M code on the same day as manipulation?
Yes, but you must append modifier 25 to the E/M code to indicate it was a separately identifiable service, preventing the claim from being automatically bundled and denied.
4. Why does chiropractic have such a high Medicare improper payment rate?
CMS data shows a 33.6% improper payment rate, driven largely by maintenance care billed as active treatment and documentation that doesn't clearly support the number of spinal regions billed.
5. What are the five spinal regions used for CMT coding?
Cervical, thoracic, lumbar, sacral, and pelvic. Document each treated region individually, with subluxation findings, to support the billed code.
6. Can chiropractors bill therapy codes like 97110 or 97140 alongside manipulation?
Yes, these follow the same timed, 15-minute-unit billing structure used broadly in musculoskeletal care, governed by the same 8-minute rule that applies to physical therapy billing.
7. Is CPT 98943 used often in chiropractic billing?
Less frequently than the spinal CMT codes. 98943 covers extraspinal regions - extremities, head, ribs, or abdomen - and is billed only when manipulation targets these areas specifically.