The AT modifier checklist that keeps Medicare from calling it maintenance care
Medicare pays 98940, 98941, and 98942 only when the -AT modifier says you are correcting an active problem and the note actually proves it. Drop the AT, or bolt it onto a visit that reads like maintenance, and the claim flips to a non-covered service the patient owes. Run this pre-claim checklist before the claim leaves your office.
Spinal CMT is covered. Extraspinal and maintenance are not.
Region count sets the code. The manipulation must target a documented subluxation of the spine. 98943 for extraspinal regions is statutorily excluded under Medicare, no matter how good the note is.
The five Medicare spinal regions: cervical, thoracic, lumbar, sacral, pelvic. Match the number of regions with a documented subluxation to the code, never the number of segments you adjusted.
Active treatment vs maintenance: the distinction the AT modifier makes
Active / corrective treatment
- Acute new injury, exacerbation, or a chronic subluxation you expect to improve or arrest from deteriorating.
- Functional goals written in the plan and objective measures that show progress.
- PART exam supports a subluxation at the level being adjusted.
Maintenance therapy
- Care to prevent disease, promote health, or preserve gains already reached.
- No reasonable expectation of further functional improvement.
- Care that has plateaued and become supportive rather than corrective.
Four gates every 98940 to 98942 line clears before it ships
The AT modifier is only a flag. What defends it is documentation the manual actually asks for. Hover any item to check it off in your head, then check it off in the chart.
Region and code integrity
Set the code from documented subluxated regions, not segments touched.
- Number of spinal regions with a documented subluxation matches 98940 / 98941 / 98942.
- Every adjusted region carries a primary subluxation dx M99.00-M99.05 plus a secondary neuromusculoskeletal dx.
- Any extraspinal work is billed 98943 with -GY, never rolled into a spinal code.
The PART exam is on the page
Subluxation is demonstrated by exam findings, not asserted.
- 2 of 4 PART findings documented, at least one being Asymmetry or Range-of-motion abnormality.
- Pain, Asymmetry, ROM, Tissue tone changes each tied to a named spinal level.
- Subluxation demonstrated by exam (PART) or X-ray, with the level of subluxation stated.
Medical necessity: the acute/chronic test
The reason this visit is corrective, in the provider's words.
- Present illness described: onset, mechanism, duration, intensity, location, radiation, aggravating and relieving factors.
- Condition characterized as acute, chronic with expected improvement, or expected arrest of deterioration.
- Subsequent visits show measurable progress against the goals, not a repeating template.
Treatment plan and modifier
The plan is what separates -AT from -GA at claim time.
- Plan states recommended level of care, functional goals, objective measures, and the date of initial treatment.
- -AT appended only when every gate above holds for this date of service.
- When care has become maintenance, an ABN is on file and -GA is used instead of -AT.
The three questions that decide AT vs ABN
Is there a documented subluxation and PART exam?
No subluxation demonstrated means no covered CMT, regardless of modifier.
Is this acute, or chronic with expected benefit?
You must reasonably expect improvement or arrest of deterioration for this visit.
Does the plan set goals and show progress?
Goals plus objective measures are what a reviewer reads to confirm active care.
Four modifiers, one decision
2026 guidelines this checklist is built on
Medicare Benefit Policy Manual, Ch. 15, Sec. 240
The controlling coverage rule for chiropractic services, including the subluxation requirement and the medical-necessity standard in 240.1.3.
Medicare Claims Processing Manual, Ch. 12, Sec. 220
Billing instructions for 98940-98942, the -AT modifier, and how maintenance claims are handled.
CMS Change Request 3449 (-AT modifier)
The transmittal that created the Active Treatment modifier and made it mandatory to distinguish active care from non-covered maintenance.
CY 2026 Medicare Physician Fee Schedule final rule
Sets the current-year CMT payment rates and the RVU framework these codes are reimbursed under.
CMS CERT and OIG improper-payment findings
Chiropractic maintenance therapy is a long-standing top improper-payment category, which is exactly what this pre-claim gate is designed to keep you out of.
ICD-10-CM M99.00 to M99.05 and your MAC's chiropractic article
Segmental and somatic dysfunction codes for the primary subluxation, paired with the local billing and documentation guidance from Novitas, Noridian, WPS, or your regional MAC.
Turn this checklist into a clean-claim workflow, not a one-time audit
Most chiropractic denials we clean up are not coding mistakes. They are documentation gaps where an active-treatment visit was billed like maintenance, or a maintenance visit was billed like active care. ASP-RCM builds the pre-claim scrub, the PART and treatment-plan checks, and the AT-vs-ABN logic into your billing so the acute/chronic test runs before the claim ever reaches your MAC. That is fewer takebacks, cleaner AT lines, and a patient-liability process that holds up on review.
Talk to our chiropractic RCM teamEducational summary of Medicare chiropractic coverage as of 2026. It does not replace the current Medicare manuals, your MAC's articles, or the advice of a qualified coding and compliance professional. Verify code descriptors, modifier policy, and payment rates against the active-year source before billing.
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