Chiropractic billing services exist to solve a narrow but unforgiving problem: chiropractic has one of the tightest Medicare benefits in all of medicine, and nearly everything a chiropractor does outside spinal manipulation falls outside it. The coding itself is simple — four CPT codes, one critical modifier — but the documentation standard behind those codes is where practices get into trouble. Payment turns almost entirely on whether the record proves active, corrective treatment of a subluxation rather than maintenance care. Our medical billing for chiropractors service page sets out how we handle that day to day.
What does Medicare actually cover for chiropractic care?
The Medicare chiropractic benefit is limited to manual manipulation of the spine to correct a subluxation. Per the CMS MLN article on Medicare coverage for chiropractic services, coverage requires a direct therapeutic relationship to the patient’s condition and a reasonable expectation of recovery or improvement of function.
Everything else is excluded. The CGS Medicare chiropractic fact sheet states plainly that “no other diagnostic or therapeutic service furnished by a chiropractor or under the chiropractor’s order is covered” — including X-rays, CT, and MRI ordered or interpreted by a chiropractor, evaluation and management services, physical medicine modalities, and manipulation of extraspinal regions.
This is not a nuance to work around — it is the shape of the benefit, and it defines the billing strategy for any chiropractic practice with Medicare patients. In an audit of chiropractic services paid in 2013, the HHS Office of Inspector General found that $358.8 million, or approximately 82 percent, of the $438.1 million Medicare paid for chiropractic services was unallowable (Report A-09-14-02033, issued October 18, 2016) — the most recent OIG national audit of this benefit — largely because the services were maintenance therapy rather than active treatment.
How is spinal manipulation coded by region?
Chiropractic manipulative treatment is coded by the number of distinct spinal regions treated. Medicare recognizes five: cervical (including the atlanto-occipital joint), thoracic (including the costovertebral and costotransverse joints), lumbar, pelvic (sacroiliac joint), and sacral.
| CPT code | Descriptor | Medicare status |
|---|---|---|
| 98940 | Chiropractic manipulative treatment (CMT); spinal, one or two regions | Covered when active/corrective treatment is documented |
| 98941 | Chiropractic manipulative treatment (CMT); spinal, three to four regions | Covered when active/corrective treatment is documented |
| 98942 | Chiropractic manipulative treatment (CMT); spinal, five regions | Covered when active/corrective treatment is documented |
| 98943 | Chiropractic manipulative treatment (CMT); extraspinal, one or more regions | Not covered by Medicare — extraspinal regions include the head, upper and lower extremities, rib cage, and abdomen |
Region counting is where honest practices make honest mistakes. A region is an anatomical region, not a segment: adjusting T1 through T3 and T10 through T12 in the same visit is one region, thoracic, not two. Coding 98941 when the record supports 98940 is the most common upcoding pattern in chiropractic, and it is visible in payer data because the ratio between the two codes is easy to profile.
The primary diagnosis on a Medicare chiropractic claim must be the subluxation, identified to the level treated. The relevant ICD-10-CM codes for segmental and somatic dysfunction are M99.00 (head region), M99.01 (cervical region), M99.02 (thoracic region), M99.03 (lumbar region), M99.04 (sacral region), and M99.05 (pelvic region). A secondary diagnosis should describe the neuromusculoskeletal condition producing the symptoms, and the two must correspond: per CGS, “the level of spinal subluxation must bear a direct causal relationship to the patient’s symptoms, and the symptoms must be directly related to the level of the subluxation that has been diagnosed.”
What does the AT modifier actually mean?
HCPCS modifier AT is defined as acute treatment, and its official descriptor instructs that it be used when reporting 98940, 98941, and 98942. Medicare treats it as the flag for active or corrective treatment.
The rule has been in force since October 1, 2004. Per the CMS billing and coding guidelines for chiropractic services, every claim containing 98940, 98941, or 98942 must include the AT modifier if active or corrective treatment is being performed — and “claims without the AT modifier will be considered as maintenance therapy and denied.”
Two misunderstandings cost practices money in opposite directions:
- The AT modifier is not a payment switch. CGS is explicit that modifier AT must only be used when the manipulation is reasonable and necessary, and its presence does not guarantee payment. Contractors deny after medical review, and appending AT to maintenance visits is exactly the pattern audits look for.
- Omitting AT on genuinely active treatment is a self-inflicted denial. If the record supports corrective care and the modifier is missing, the claim is denied as maintenance anyway.
The modifier is a statement about clinical intent, and the chart has to make the same statement independently. Practices that treat AT as a billing macro rather than a documentation-driven decision end up with denial patterns worth working through a structured denial management and appeal workflow, because the fix is upstream in documentation, not downstream in resubmission.
When does care become maintenance, and where does the ABN fit?
CMS draws the line at clinical improvement. Per the CMS documentation checklist for chiropractic doctors, “Medicare only pays for active or corrective treatment to correct acute or chronic subluxation,” and “once the injury is stable, more treatment is maintenance therapy and isn’t covered.” CGS frames the same transition as the point where “further clinical improvement cannot reasonably be expected.”
Crossing that line is not a billing failure. Many patients benefit from ongoing supportive care; it simply is not a Medicare-covered service, and the practice’s obligation is to tell the patient so before the visit happens. That is the function of the Advance Beneficiary Notice of Noncoverage, Form CMS-R-131. When the provider believes a service is likely to be denied as not medically necessary, the beneficiary signs the ABN and the claim carries the appropriate modifier.
| Modifier | Official descriptor | When it applies in chiropractic |
|---|---|---|
| AT | Acute treatment (this modifier should be used when reporting service 98940, 98941, 98942) | Active or corrective treatment of an acute or chronic subluxation. Never on maintenance care. |
| GA | Waiver of liability statement issued as required by payer policy, individual case | A signed ABN is on file for a service expected to be denied as not medically necessary, typically maintenance care. |
| GY | Item or service statutorily excluded, does not meet the definition of any Medicare benefit or, for non-Medicare insurers, is not a contract benefit | Services outside the chiropractic benefit altogether, such as 98943 for extraspinal manipulation. |
| GZ | Item or service expected to be denied as not reasonable and necessary | Used in the rare instance where a denial is expected and no ABN was obtained. The claim will not be paid and the patient cannot be billed. |
A practice with a working ABN process converts an unpaid denial into a collectible patient balance, legitimately and transparently. A practice without one absorbs the loss.
What documentation proves medical necessity?
An X-ray is no longer required to demonstrate subluxation. CMS accepts either imaging — an X-ray taken within 12 months before or 3 months after treatment begins, or a CT or MRI — or examination findings using the P.A.R.T. criteria.
Per Noridian’s chiropractic documentation guidelines, the examination must document at least two of the four P.A.R.T. elements, and at least one of those two must be asymmetry/misalignment or range of motion abnormality:
- P — Pain/tenderness, evaluated in terms of location, quality, and intensity
- A — Asymmetry/misalignment identified on a sectional or segmental level
- R — Range of motion abnormality
- T — Tissue and tone changes in the characteristics of contiguous or associated soft tissues
Beyond P.A.R.T., the initial visit record needs a history including the mechanism of trauma and the onset, duration, intensity, frequency, location, and radiation of symptoms; an examination establishing the subluxation; a primary diagnosis naming the level of subluxation with a supporting secondary diagnosis; a treatment plan; and the date of initial treatment. CMS requires that date, or the date of the exacerbation, to be entered in Item 14 of the CMS-1500 form or its electronic equivalent.
The treatment plan is what auditors reach for first, because it is what makes “active treatment” testable. It must state the recommended duration and frequency of care, specific goals, and objective measures used to evaluate effectiveness. Without those measures, there is no way to demonstrate the improvement that distinguishes covered care from maintenance.
Subsequent visits require an interval history documenting changes since the last visit, an examination of the involved region using the P.A.R.T. elements, an assessment of effectiveness against the stated goals, and documentation of the exact segments treated that day.
Chiropractic is not alone in this: podiatry billing services face the same structure, where a statutory exclusion is overcome only by documenting a qualifying clinical condition. In both specialties the claim looks clean and fails on review, which is why the documentation itself is the usual subject of a medical billing audit.
What should chiropractic billing services do beyond submitting claims?
Claim submission is the easy part of a four-code specialty. A billing partner earns its place where coding meets compliance:
- Watching the treatment-plan clock. Flagging patients approaching the end of a documented plan of care, before those visits become undocumented maintenance billed with an AT modifier.
- Auditing the region-count distribution. A practice whose 98941 volume dwarfs its 98940 volume should know that before a payer does.
- Running the ABN process as a workflow. Not as a form someone remembers at the front desk.
- Managing non-Medicare payers on their own terms. Commercial plans, personal injury, and workers’ compensation each carry visit limits, authorization rules, and documentation expectations that look nothing like Medicare’s.
- Reporting that connects documentation to dollars. Tracking monthly billing KPIs alongside days in A/R lets you see a documentation problem while it is still a trend rather than a recoupment. Our guide to evaluating a medical billing company lays out what else to ask.
Frequently asked questions
Does Medicare ever pay for CPT 98943?
No. CPT 98943 describes extraspinal chiropractic manipulative treatment, and Medicare does not cover manipulation of extraspinal regions — the head, upper and lower extremities, rib cage, and abdomen. Some commercial plans do cover it, so verify each contract. When billing Medicare for a statutorily excluded service, the GY modifier applies.
Can a chiropractor bill Medicare for an evaluation and management visit?
No. The benefit covers manual manipulation of the spine to correct a subluxation; no other diagnostic or therapeutic service furnished by a chiropractor or under a chiropractor’s order is covered. Examination time is real work, but under Medicare it supports medical necessity for the manipulation rather than being separately payable.
Do we still need an X-ray to document subluxation?
Not necessarily. Subluxation may be demonstrated by imaging — an X-ray taken within 12 months before or 3 months after treatment begins, or a CT or MRI — or by physical examination using at least two of the four P.A.R.T. criteria, one of which must be asymmetry/misalignment or range of motion abnormality.
What happens if we forget the AT modifier on an active-treatment claim?
Medicare treats a claim without the AT modifier as maintenance therapy and denies it. If the documentation supports active or corrective treatment, the claim can be corrected and resubmitted — but a recurring pattern of missing modifiers is a workflow problem, and should be fixed at the point of charge entry.
Verify current CPT, ICD-10, and payer requirements before billing.
Talk with a billing team that knows chiropractic
AMS Solutions, Inc. has billed for medical practices since 1992. The company is physician-founded, staffs coding with AAPC-certified (CPC, CPB) coders, operates under a signed BAA, and will map in writing which functions are performed where. We aim to be the billing team a practice keeps, not one it re-tenders, which in chiropractic means paying as much attention to your plans of care and ABN process as to your claim submissions. Get in touch through our contact form for a review of your AT modifier and ABN workflow, or call 866-973-2221.
