The AT modifier is not a formality
Here is the short answer. The AT modifier tells Medicare you are delivering active treatment, not maintenance care. It does not prove medical necessity on its own. When a reviewer opens an AT-flagged 98940, 98941, or 98942, they are reading your note for one thing: proof the patient is still expected to improve. If the language is not there, the AT does not save the claim.
98940 / 98941 / 98942
to correct a subluxation
to maintenance of function
The AT modifier is a claim about the treatment, not a stamp on the claim.Medicare Benefit Policy Manual · Ch. 15 · §240
Active treatment and maintenance care are the same adjustment. Only one gets paid.
Medicare defines the difference by intent and by trajectory, not by technique. Same hands, same table, same segment. What separates them is whether the record shows a reasonable expectation of measurable improvement.
Active / corrective treatment
A reasonable expectation the manipulation will restore or improve function tied to an acute or chronic subluxation.
- New or acute injury, exacerbation, or a documented flare of a chronic condition
- Objective functional deficit at the segment being treated
- A treatment plan with measurable goals and an expected endpoint
- Note shows progress, or a documented reason care is being adjusted
Maintenance therapy
Care to prevent deterioration, maintain a plateau, or promote general wellness once the condition is stable.
- Patient has reached maximum therapeutic benefit for this episode
- Goal is to preserve current status, not recover lost function
- "Feels good," "tune-up," "keeps him mobile," "supportive care"
- Same note repeated visit over visit with no measurable change
The only spinal CMT codes on the benefit
Medicare covers manual manipulation of the spine to correct a subluxation, and nothing beyond it. Extraspinal manipulation is a real service, but it is not a Medicare benefit, so no modifier rescues it.
A reviewer denies the documentation, not the adjustment.Operator note · what the AT flag actually triggers
Subluxation is documented in four letters: PART
Medicare accepts the subluxation by physical exam using the PART criteria. At least two of the four must be present, and one of them must be Asymmetry or Range of motion. This is the exam finding that anchors the whole AT claim.
Pain / Tenderness
Location, quality, and provocation of pain at the segment, by observation and description.
Asymmetry
Misalignment or postural asymmetry on inspection, static or motion palpation. Counts toward the required pair.
Range of motion
Increase, decrease, or aberrant motion of the segment. Counts toward the required pair.
Tissue / Tone
Changes in soft tissue: tone, temperature, texture. Supports the finding but cannot stand alone.
The path an AT-flagged manipulation walks
Every step is a place the claim either earns the payment or hands the reviewer a reason to deny. The modifier gets you into the review. The record gets you through it.
Initial visit establishes the episode
History, symptoms, the subluxation by PART or imaging, and the date of the initial treatment.
Treatment plan sets a target
Recommended level of care, frequency, duration, objective measures, and specific functional goals.
Subsequent visit shows the trajectory
Interval history, updated exam, and documented progress toward the stated goals, or the clinical reason it changed.
Plateau without a re-injury or flare
Notes stop showing change. Goals are met or care is now preserving status. This is where the AT flag stops matching the record.
Rewrite the phrases reviewers read as maintenance
Most AT denials are not clinical failures. They are documentation habits. The same visit, described in functional terms with a measurable target, reads as active treatment instead of a wellness tune-up.
The 2026 guidance behind every point above
Medicare Benefit Policy Manual, Chapter 15, Section 240
Defines covered chiropractic services: manual manipulation of the spine to correct a subluxation, codes 98940 to 98942. Sets the active-treatment versus maintenance-therapy distinction and the PART exam criteria for documenting subluxation.
CMS Pub. 100-02, Ch. 15 §240 & §240.1.3CMS CY2026 Physician Fee Schedule Final Rule
Confirms the CY2026 payment framework for spinal CMT and continues the AT-modifier active-treatment policy. Coverage of 98940 to 98942 and the exclusion of extraspinal 98943 remain unchanged for the 2026 benefit year.
CMS-1832-F · CY2026 PFSAT modifier: active treatment attestation
The AT modifier signals active or corrective treatment and is required on covered CMT claims. CMS is explicit that AT does not by itself establish medical necessity; the underlying documentation must support it.
CMS AT-modifier guidance · MLN chiropractic servicesDocumentation requirements for coverage
Initial and subsequent visit elements: history, subluxation by PART or imaging, a treatment plan with objective goals and expected duration, and documented progress across the episode of care.
CMS Pub. 100-02, Ch. 15 §240.1.2 to §240.1.5We build the note the reviewer is looking for, before the claim goes out.
Our chiropractic billing team scrubs every AT-flagged CMT line against the active-treatment standard: PART documented, functional goals measurable, progress traceable across the episode. Fewer maintenance-denials, cleaner audits, and appeals that hold because the record already carries the proof. That is the difference between a modifier and a paid claim.
Get a chiropractic AT-modifier reviewDenial-defense documentation · CMT coding integrity · audit-ready records
This article is operational guidance for chiropractic billing teams and reflects Medicare policy as published in the Medicare Benefit Policy Manual Chapter 15 Section 240 and the CMS CY2026 Physician Fee Schedule Final Rule. It is not legal or coding-certification advice. Verify current requirements with your Medicare Administrative Contractor, since local coverage determinations can add documentation specifics for your jurisdiction.
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