Denials for chiropractic CPT code claims happen much more often than expected, and not because the services were never rendered. Chiropractic CPT code coverage under Medicare is limited and highly specific, so it only takes one modifier or code that does not line up with the rest of the claim to get the whole thing denied.
The Med Bridge LLC chiropractic billing codes guide reviews the CPT codes chiropractors use, the ICD-10 codes required to accompany them, the modifiers that determine whether a claim gets paid, and the errors that most often show up in denied claims.
The Core CPT Codes: 98940 to 98943
Chiropractic CPT codes for manipulative treatment, usually called CMT, are billed based on how many spinal regions were treated in a single visit, not how many individual adjustments were made. There are five recognized spinal regions in chiropractic billing codes: cervical, thoracic, lumbar, sacral, and pelvic.
98940: Covers manipulation of 1 to 2 spinal regions
9894: Covers manipulation of 3 to 4 spinal regions, and it’s the most commonly billed of the three
98942: Covers manipulation of all 5 spinal regions
98943: Covers manipulation of an extra-spinal region, such as the shoulders, knees, wrists, ribs, or TMJ
You can’t bill two of these codes for the same date of service on the same patient. A solid chiropractic billing code guide will tell you to pick the one code that reflects the total number of regions actually treated and documented that visit, not the number you usually bill and not a rounded-up estimate.
98943 sits in its own category. Medicare doesn’t cover it under any circumstance, whether the care is active or maintenance. If you’re billing it to Medicare, it needs a GY modifier to flag it as a statutorily excluded service. If it’s billed on the same day as a spinal CMT code, it also needs modifier 59 to show it’s a distinct service at a different site.
Why the AT Modifier Decides Everything
If there’s one thing to get right in any chiropractic billing guide, it’s this. Every Medicare claim for 98940, 98941, or 98942 needs the AT modifier when the treatment is active and corrective.
Medicare’s chiropractic benefit covers exactly one thing: manual manipulation of the spine to correct a subluxation, and only when that manipulation is actively working toward a measurable outcome. Maintenance care, where the goal is simply keeping the patient comfortable rather than correcting a documented condition, isn’t covered at all.
Leave the AT modifier off an active treatment claim, and Medicare reads it as maintenance by default and denies it automatically, often with no chart review and no appeal path. Attach AT to a claim that your own notes describe as maintenance, and you’ve created the opposite problem: a mismatch between the modifier and the documentation, which is one of the most common findings in chiropractic Medicare audits.
The rule of thumb is simple. AT isn’t a default you apply to every claim. It’s a claim you make about the clinical picture, and the chart has to back it up.
When Maintenance Care Starts: GA and GZ
Once a patient plateaus and stops showing measurable improvement, Medicare no longer considers the care active, even if the chiropractor believes ongoing adjustments still have value. At that point, two modifiers come into play.
GA signals that a waiver of liability is on file, meaning the patient signed an Advance Beneficiary Notice of Noncoverage (ABN) acknowledging that Medicare likely won’t pay and they’ll be responsible for the cost.
GZ signals that the service is expected to be denied as not reasonable or necessary, and no ABN is on file.
In practice, this part of a chiropractic billing guide comes down to timing. The moment a patient’s progress plateaus, issue an ABN before continuing treatment, stop appending AT, and bill ongoing visits with GA instead. Continuing to bill AT past the point of documented improvement is one of the patterns that shows up most often in OIG recoupment findings.
ICD-10 Diagnosis Pairing: Getting the M99.0x Codes Right
The primary diagnosis on a Medicare chiropractic claim has to be a subluxation code from the M99.0x family, matched to the specific region treated.
M99.01: for the cervical region
M99.02: for the thoracic region
M99.03: for the lumbar region
M99.04: for the sacral region
M99.05: for the pelvic region
A secondary diagnosis describing the clinical condition, such as low back pain, radiculopathy, or cervicalgia, supports medical necessity alongside the subluxation code. One detail worth flagging for anyone still working from an older code list: as of October 2025, ICD-10 code M54.5 (low back pain, unspecified) was retired and split into three more specific codes, M54.50, M54.51, and M54.59. Any claim still carrying the old M54.5 code will be denied outright, so it’s worth checking that superbills and EHR pick lists have been updated.
Documentation should also reflect PART criteria: Pain/tenderness, Asymmetry, Range of motion abnormality, and Tissue tone changes. At least two of the four need to be present, and one of those two has to be range of motion or tissue tone, to support the subluxation diagnosis at each visit.
Other Modifiers Worth Knowing
Beyond AT, GA, and GZ, a few other modifiers come up regularly in chiropractic billing procedure codes.
Modifier 25: Gets appended to an E/M code when a significant, separately identifiable evaluation is performed on the same day as a manipulation. Without it, the E/M service tends to get bundled into the CMT code and denied on its own.
Modifier 59: More specific X{EPSU} modifiers unbundle services that would otherwise be considered part of another procedure on the same date, such as billing 98943 alongside a spinal CMT code.
Misapplied modifiers are one of the leading causes of denials industry-wide, not because the underlying code was wrong, but because the modifier told the payer something the documentation didn’t support.
Common Reasons for Chiropractic CPT Codes Claims Get Denied
A few patterns account for most of the denials chiropractic practices see, and any practical chiropractic billing procedure guide should walk through them directly.
Missing or Mismatched AT Modifier. Covered above, and still the single biggest driver of automatic denials.
Region Count Mismatch. Billing 98942 when the notes only support manipulation of three regions, or billing 98941 with documentation that only describes two. Payers increasingly run automated checks specifically looking for this pattern.
Generic or Missing Subluxation Coding. Billing a pain code alone, without the corresponding M99.0x subluxation code tied to the region treated, is one of the most common reasons a claim gets flagged for lack of medical necessity.
Maintenance Care Billed as Active Treatment. Once a patient plateaus, continuing to bill AT instead of switching to an ABN and GA isn’t just a denial risk. It’s a compliance issue, and the pattern most likely to trigger a broader audit.
Missing ABN when one was needed. If a service is expected to be denied and no ABN is on file, the practice, not the patient, usually absorbs the cost.
Best Practices for Cleaner Chiropractic CPT Code Claims
A few habits consistently show up in practices with lower denial rates. Document the exact regions treated at every visit rather than writing a general note. Confirm PART criteria are met and recorded before applying a subluxation code. Review patient progress often enough to catch the plateau point before it turns into a compliance issue. Keep ABN forms current and signed before, not after, a service that’s likely to be denied.
Following these habits consistently is really what separates a chiropractic billing guide from an actual working billing process.
Conclusion
Chiropractic billing code rewards precision more than most specialties. The right CPT code, the right region count, a subluxation diagnosis that matches the region treated, and a modifier that accurately reflects whether care is active or maintenance all have to line up, or the claim comes back. None of it is complicated once the workflow is built around it. It just has to be built correctly the first time, which is the whole point of putting together a chiropractic billing procedure code guide like this one.
If your practice is dealing with recurring chiropractic denials, or you want billing set up correctly from the start, Med Bridge LLC can help. Contact our team to learn how our medical billing and coding services can keep your chiropractic CPT code claims accurate and your reimbursements consistent.
FAQs
When does care become maintenance, and how do I bill it (GA vs GZ)?
Maintenance occurs when a patient reaches a plateau and no longer shows measurable improvement. Then stop using AT. Please bill GA (ABN on file) before treatment. Use GZ if there is no ABN on file and you expect the service to be denied. Most practices will absorb the cost without the ABN before the service.
Which ICD-10-CM codes should I pair with CMT?
A subluxation code must match the region treated: M99.01 (cervical), M99.02 (thoracic), M99.03 (lumbar), M99.04 (sacral) or M99.05 (pelvic). In case of neck or low back pain, add M54.50, M54.51, or M54.59 as a secondary diagnosis. An explanation.
What are the PART criteria, and how many do I need?
Symptoms include pain, asymmetry, misalignment, a change in tone, or inflammation. One must be both asymmetric and range of motion. Every visit should support the M99.0x diagnosis.
Can a chiropractor bill an E/M visit with the CMT modifier (25)?
Medicare does not cover E/M visits by chiropractors, only manual manipulation of the spine. Payers may allow E/M with modifier 25 on the same day as CMT. A distinctive evaluation should be added to the note.
How do I appeal a denied chiropractic claim?
Denials can be technical (modifiers or codes mismatched) or clinical (medical necessity). Resubmit with corrections. In case of clinical denials, send treatment plans, PART findings, progress notes, and payer’s policy. Medicare redetermination requests generally have a 120-day deadline.
When should a chiropractic practice outsource billing?
In the event that AT, GA, and GZ errors result in denials or ABNs are handled inconsistently, you might want to consider it. ABN workflows, modifier accuracy, and appeals knowledge are important. Med Bridge LLC can perform a free billing audit.
What is chiropractic billing?
Chiropractic billing codes are based on spinal regions treated (CPT 98940 to 98943), diagnosis, and modifiers. Medicare pays for modifiers and documentation.
