Chiropractic Billing Basics: Codes, Modifiers And Common Denials

Chiropractic billing basics: CMT codes 98940 to 98943, E/M codes, M99.0x subluxation diagnoses, AT, GA, GZ, GY, 25 and 59 modifiers, and how to fix denials.

Chiropractic billing looks simple from the outside: a small set of manipulation codes, a few exam codes and some modifiers. In practice it is one of the most denial-prone areas of outpatient billing, because Medicare covers only a narrow slice of chiropractic care, commercial payers each add their own rules, and small documentation gaps turn into unpaid claims.

The short answer: most chiropractic billing codes fall into four groups. Claims are built from chiropractic manipulative treatment (CMT) codes 98940 to 98943, evaluation and management (E/M) codes when a separate exam is justified, a subluxation or musculoskeletal diagnosis, and modifiers such as AT, GA, GZ, GY, 25 and 59 that tell the payer how to treat the service. Get those four pieces right and supported by your notes, and most denials disappear.

This guide is a practical chiropractic billing cheat sheet for practice owners and front office teams. It explains what each code and modifier means, the Medicare rules that cause the most trouble and the denials worth fixing first. It is general education, not coding or legal advice: always confirm details against your Medicare Administrative Contractor (MAC), each commercial payer’s policy and the current AMA CPT code set. For the wider picture of growing a practice, see our chiropractic marketing hub.

The Core Chiropractic CPT Codes

CPT codes describe what you did. For chiropractic care, the manipulation codes are defined by the number of body regions treated, so your notes must show which regions were adjusted and why.

Chiropractic Manipulative Treatment (CMT) Codes

Code	What It Describes	Medicare Status
98940	CMT, spinal, one to two regions	Covered when billed for active treatment of subluxation with the AT modifier
98941	CMT, spinal, three to four regions	Covered when billed for active treatment of subluxation with the AT modifier
98942	CMT, spinal, five regions	Covered when billed for active treatment of subluxation with the AT modifier
98943	CMT, extraspinal, one or more regions	Not covered by Medicare

The five spinal regions recognized for these codes are cervical, thoracic, lumbar, sacral and pelvic (sacroiliac). Extraspinal regions include the head, upper and lower extremities, rib cage and abdomen. Commercial payers often cover 98943, but Medicare does not, which is why it shows up in so many Medicare denials.

Evaluation And Management (E/M) Codes

E/M codes describe office visits and exams. The office and outpatient codes most practices use are:

• New patients: 99202 to 99205 (99201 was deleted in 2021).
• Established patients: 99211 to 99215.

The CMT codes already include a pre-manipulation patient assessment. A separate E/M is billable only when the visit includes a significant, separately identifiable evaluation beyond that routine assessment, such as a new patient exam, a re-examination or a new injury. That is what modifier 25 signals (see below). Medicare does not cover E/M services performed by chiropractors, so those visits are billed to Medicare only when the patient asks for a formal determination, typically with the GY modifier.

Other Codes Common In Chiropractic Offices

Many practices also bill therapy and modality codes to commercial payers, such as 97110 (therapeutic exercise), 97112 (neuromuscular re-education), 97140 (manual therapy techniques) and 97530 (therapeutic activities). These are time-based codes billed in 15-minute units, and payer rules on who may perform them, how time is counted and which combinations are allowed vary widely. Medicare does not cover these services when furnished by a chiropractor.

ICD-10 Diagnosis Coding For Chiropractors

Diagnosis codes explain why you provided the service. Payers deny claims when the diagnosis does not support the procedure or is not specific enough.

Medicare Subluxation Codes

Medicare covers chiropractic only for manual manipulation of the spine to correct a subluxation, so the primary diagnosis on a Medicare chiropractic claim must be the subluxation, at the level treated. In ICD-10-CM these are the segmental and somatic dysfunction codes in the M99.0x range. Medicare contractor policies commonly list:

ICD-10 Code	Region
M99.01	Segmental and somatic dysfunction of cervical region
M99.02	Segmental and somatic dysfunction of thoracic region
M99.03	Segmental and somatic dysfunction of lumbar region
M99.04	Segmental and somatic dysfunction of sacral region
M99.05	Segmental and somatic dysfunction of pelvic region

The neuromusculoskeletal condition that made treatment necessary is listed as the secondary diagnosis. Each MAC publishes which secondary codes it accepts and how they must pair with the subluxation levels, so check your contractor’s Local Coverage Determination (LCD) and billing article rather than relying on a generic list. Code to the highest level of specificity available.

Commercial Payer Diagnosis Rules

Commercial payers do not always require subluxation codes. Many accept musculoskeletal diagnoses directly, such as cervicalgia (M54.2) or low back pain codes in the M54.5x range, and some cap visits per diagnosis or per year. Read each major payer’s chiropractic policy at least once a year.

Chiropractic Modifiers You Need To Know

Modifiers add information that changes how a payer processes a line. Using the wrong one, or leaving one off, is behind a large share of chiropractic claim denials.

Modifier	Meaning	When It Is Used
AT	Acute treatment	Required by Medicare on 98940 to 98942 for active or corrective treatment of acute or chronic subluxation. Claims without it are treated as maintenance and denied.
GA	Waiver of liability on file	Medicare: you expect the service to be denied as not reasonable and necessary, and the patient signed an Advance Beneficiary Notice (ABN).
GZ	Expected denial, no ABN	Medicare: you expect a denial but no ABN was signed, so the patient cannot be billed.
GY	Statutorily excluded	Medicare: the service is never covered for chiropractors, such as 98943, exams or therapies. Used when a denial is needed, for example for a secondary payer.
25	Significant, separately identifiable E/M	Commercial payers: an E/M on the same day as CMT that goes beyond the usual pre-manipulation assessment.
59 or XS	Distinct procedural service, separate structure	Commercial payers: a procedure that is normally bundled with CMT, such as 97140, performed on a different anatomic region. Many payers prefer XS where they accept X modifiers.

The AT Modifier And Maintenance Care

Medicare pays for active or corrective treatment, meaning care that is expected to produce functional improvement. Once further clinical improvement cannot reasonably be expected, Medicare considers the care maintenance therapy, which is not covered. The AT modifier tells Medicare the care is active. It does not guarantee payment: your records must still show the subluxation, the treatment plan, measurable goals and progress. When care becomes maintenance, drop the AT modifier, and use the ABN process if the patient wants to continue.

ABNs, GA And GZ

An ABN is a written notice, signed by the patient before the service, explaining that Medicare is likely to deny the service and that the patient will be responsible for payment. With a valid ABN on file, append GA. Without one, append GZ, and you cannot bill the patient if Medicare denies. An ABN is not needed for services Medicare never covers (such as 98943), which are billed with GY when a claim is required. Your MAC’s instructions on combining these modifiers with AT are the final word.

Modifier 25 And 59 Without Overuse

Payers watch modifiers 25 and 59 closely. Use 25 only when the notes show a separate exam with its own history, examination and decision making, not on every visit. Use 59 or XS only when the bundled procedure was truly performed on a distinct region and the notes say so. Routine use of either modifier is a common audit trigger.

Medicare Rules That Cause Most Chiropractic Denials

Medicare’s chiropractic benefit is narrow, and the rules are specific. The points below come from CMS manuals and MAC billing articles.

• Only spinal manipulation is covered. Coverage extends only to manual manipulation of the spine to correct a subluxation. X-rays, exams and therapies furnished by a chiropractor are not covered.
• The subluxation must be documented. It can be shown by x-ray or by physical examination. The physical exam route uses the P.A.R.T. criteria (pain or tenderness, asymmetry or misalignment, range of motion abnormality, tissue or tone changes): two of the four are required, and one of them must be asymmetry or misalignment, or range of motion abnormality. A diagnosis of pain alone is not enough.
• X-rays must be reasonably proximate. When an x-ray is used to demonstrate the subluxation, contractor policies generally require it to have been taken no more than 12 months before the start of the course of treatment, with some exceptions for chronic conditions.
• The initiation date matters. The date the current course of treatment began goes in Item 14 of the CMS-1500 or its electronic equivalent.
• Diagnosis order matters. Subluxation level first, neuromusculoskeletal condition second.

The CMS Medicare Benefit Policy Manual, Chapter 15 contains the national rules, and your MAC’s LCD sets out the details for your region.

Documentation That Supports The Claim

Every code you bill should be traceable to the note for that date of service. For most chiropractic visits, that means:

• The patient’s subjective complaints and any change since the last visit.
• Objective findings, including P.A.R.T. findings for each region treated.
• The regions adjusted and the technique used, which must match the CMT code billed.
• The treatment plan with frequency, duration and measurable functional goals.
• Periodic re-examinations showing progress toward those goals.
• For any separately billed E/M, a clearly separate history, exam and assessment.
• For time-based therapy codes, start and stop times or total minutes for each service.

An EHR built for chiropractic can enforce much of this with templates and alerts. Our list of the best chiropractic EHR software compares the main options, and our existing guide to chiropractic practice management software covers scheduling and front office tools.

Common Chiropractic Claim Denials And How To Fix Them

Denial Cause	What Usually Went Wrong	Fix
Missing AT modifier	Active care billed to Medicare without AT	Add AT to 98940 to 98942 when care is active and documented
Maintenance care	Notes show no expected improvement	Update goals and re-exam findings, or use the ABN and GA process
98943 billed to Medicare	Extraspinal CMT is not covered	Bill with GY if a denial is needed, collect from the patient or a secondary payer
Diagnosis does not support procedure	Missing subluxation primary code or unaccepted secondary code	Check your MAC’s code pairing list and sequence correctly
Regions do not match code	98941 billed but only two regions documented	Code from the note, not from habit
Bundled service	97140 billed on the same region as CMT	Treat a different region and document it, then use 59 or XS where allowed
E/M bundled into CMT	Modifier 25 without a separate exam in the notes	Bill E/M only for significant, separately identifiable work
Eligibility or visit limits	Plan inactive, visit cap reached or authorization missing	Verify benefits and authorization before the first visit and at each plan year
Provider not credentialed	Doctor not enrolled with the payer	Complete enrollment before treating that payer’s patients
Timely filing	Claim sent after the payer’s deadline	Submit claims within days and work rejections daily

A Simple Denial Workflow

• Scrub claims before submission with payer-specific edits, either in your billing software or with your billing service.
• Work rejections (claims that never entered the payer’s system) every day, and denials at least weekly.
• Group denials by cause each month and fix the upstream problem: a template, a front desk step or a payer setup error.
• Appeal with documentation when the service was billed correctly, and track appeal outcomes.

In-House Billing, Software Or A Billing Service

Small practices often start by billing in-house with a front desk team and practice management software. As volume and payer mix grow, many move to a dedicated biller or an outsourced billing service. The right answer depends on claim volume, how much Medicare and personal injury work you do, and whether anyone on staff has time to work denials consistently. Whichever model you choose, the practice remains responsible for what is billed under its provider numbers, so keep someone internally who understands the basics in this guide.

Who To Hire: ReVerb Chiropractic Lists

If you want help with billing, coding or the payer setup behind it, these ReVerb lists profile options we checked against each company’s own site:

• Best chiropractic billing services and companies for practices that want to outsource claims, posting and denial management.
• Best chiropractic billing software for practices that keep billing in-house and need strong claim scrubbing.
• Best chiropractic credentialing services for enrolling new doctors and locations with Medicare and commercial payers.

Frequently Asked Questions

What Are The Main CPT Codes For Chiropractic Billing?

The core codes are 98940 (one to two spinal regions), 98941 (three to four spinal regions), 98942 (five spinal regions) and 98943 (extraspinal regions). New patient E/M codes are 99202 to 99205 and established patient codes are 99211 to 99215.

Does Medicare Cover Chiropractic Care?

Medicare Part B covers manual manipulation of the spine to correct a subluxation when it is active or corrective treatment. It does not cover maintenance care, extraspinal manipulation (98943), or exams, x-rays and therapies furnished by a chiropractor.

What Does The AT Modifier Mean?

AT stands for acute treatment. Medicare requires it on 98940, 98941 and 98942 when the manipulation is active or corrective treatment of an acute or chronic subluxation. Claims without AT are treated as maintenance therapy and denied.

When Should A Chiropractor Use An ABN?

Use an ABN when you expect Medicare to deny a normally covered service as not reasonable and necessary, most often when care has become maintenance. The patient signs it before the service, and the claim carries the GA modifier.

Conclusion

Chiropractic billing rewards consistency. Code CMT from the regions you actually documented, put the right diagnosis in the right order, use AT, GA, GZ and GY exactly as Medicare intends, and reserve modifiers 25 and 59 for visits that truly need them. Verify benefits before care starts, keep notes that show progress toward goals and review denials by cause every month. Rules change, so treat this guide as a starting checklist and confirm the details with your MAC, your payers and the current CPT and ICD-10-CM code sets.