Medicare billing for chiropractors, what CMS changed and what to document

What to take away

Chiropractic provider billing under Medicare Part B pays only for active treatment by means of manual manipulation of the spine, and the AT modifier is what tells the contractor the treatment is active.
Medicare pays for the manipulation itself. Exams, x-rays, massage, ultrasound, and most modalities are statutorily excluded, so they are the patient's responsibility or another payer's.
Medicare Advantage plans set their own coverage rules, which are often broader than Original Medicare, so the same visit can be covered by one plan and denied by another.
CMS documentation expectations and OIG documentation expectations overlap: the record must show the subluxation, the level treated, the method, the patient's response, and the treatment plan.
Maintenance care is not a covered Medicare benefit. Once the patient's condition has stabilized and care is only to prevent recurrence, claims should stop.
Coding errors and cloned notes are the two failures that drive most chiropractic Medicare repayments, so internal review matters more than volume.

How the Medicare chiropractic benefit is defined under CMS rules

The Medicare chiropractic benefit is one of the narrowest benefits in Part B. Congress limited it to treatment by means of manual manipulation of the spine to correct a subluxation demonstrated by x-ray or physical exam. That language is the whole benefit. Nothing else a chiropractor does in a typical visit falls inside it.

A subluxation, for Medicare purposes, is a motion segment in which alignment, movement integrity, or physiologic function is altered, though the spinal nerves remain intact. The definition is a coverage definition, not a clinical philosophy. If the record does not describe a subluxation at a specific level, the claim has no covered service to stand on.

The benefit also requires that the manipulation be active treatment. Active treatment means the patient's condition is expected to improve, or the care is for a recent injury or flare. Care given after maximum therapeutic benefit has been reached is maintenance therapy, and Medicare does not pay for it.

A few services ride along in some circumstances. If a manipulation is covered, the evaluation and management service on the same day may be payable when it is significant and separately identifiable. Everything else, including extremity manipulation, is outside the benefit.

New practice owners often assume a license and an NPI are enough to bill Medicare. They are not. Enrollment, documentation habits, and an understanding of the benefit's boundaries come first, which is why a compliance checklist for new owners is worth building before the first claim goes out.

What the benefit does not include

Physical therapy modalities such as ultrasound, electrical stimulation, and traction
Massage therapy and manual therapy that is not spinal manipulation
X-rays and other diagnostic imaging
Orthopedic supplies, braces, and supports
Acupuncture and dry needling
Nutritional counseling and most patient education

A patient who receives any of these on the same date as a covered manipulation may still owe for them. Tell the patient in advance and keep a signed notice in the record.

Who can bill it

Only a chiropractor enrolled in Medicare, or a physician or osteopath performing the same service, may bill. Chiropractors enroll as a supplier, not as a physician, which changes the enrollment form and the fee schedule that applies. A chiropractor cannot bill for services incident to a physician's care.

The AT modifier rule and when manual manipulation of the spine is covered

The AT modifier rule is simple on its face and unforgiving in practice. AT, defined as acute treatment, is appended to the CPT code for the spinal manipulation to certify that the service is active treatment, not maintenance. The AT modifier rule exists because the code itself does not distinguish the two.

When a claim for 98940, 98941, or 98942 arrives without AT, Medicare contractors treat it as maintenance therapy and deny it. The modifier is not a billing preference. It is the condition of payment.

Some contractors have asked for documentation of the AT modifier's basis, so the note must actually support active care. A record that describes unchanged symptoms for eight weeks while the AT modifier stays on every claim invites a denial and a repayment demand.

What active treatment looks like in the note

A recent onset, a new injury, or a documented flare of a chronic condition
Objective findings that change over the course of care
A treatment plan with expected goals and a planned re-examination
Progress toward those goals, or a documented reason progress is slow

When the AT modifier should come off

When the patient reaches maximum therapeutic benefit, the AT modifier should come off and the claims should stop. If the patient elects to continue with maintenance visits, bill them as non-covered and collect from the patient, with a signed advance beneficiary notice where it applies.

Continuing to bill Medicare with AT after stabilization is the single most common compliance failure in chiropractic Medicare billing.

The manual manipulation codes

CPT code	What it describes	Typical use
98940	Chiropractic manipulative treatment, spinal, 1 to 2 regions	Short or focused visits
98941	Chiropractic manipulative treatment, spinal, 3 to 4 regions	Most common Medicare claim
98942	Chiropractic manipulative treatment, spinal, 5 regions	Full spine treatment
98943	Chiropractic manipulative treatment, extraspinal, 1 or more regions	Not covered by Medicare

The region count must match the note. If the note documents cervical and thoracic treatment, 98940 is defensible. If it documents five regions, 98942 applies. Contractors compare the code to the treated levels, and a mismatch is a coding error even when the care was appropriate.

Medicare Part B versus Medicare Advantage billing for chiropractors

Medicare Part B versus Medicare Advantage billing is where most front-desk confusion starts. Original Medicare is administered by Medicare Administrative Contractors under national and local coverage rules. Medicare Advantage is administered by private plans under a contract with CMS, and those plans may cover more than Original Medicare does.

Many Medicare Advantage plans cover maintenance visits, exams, and modalities that Part B excludes. Others follow Part B almost exactly. There is no single answer, so the plan's evidence of coverage and provider manual govern each patient.

That difference matters for chiropractic provider billing at the front desk. Staff should verify the plan type before the visit, not after the denial. A patient who moved from Original Medicare to a Medicare Advantage plan may find that care previously denied is now covered, or the reverse.

Practical differences to track

Prior authorization: some Medicare Advantage plans require it for a course of manipulation, Part B generally does not
Visit limits: plans may cap visits per year or per episode, Part B has no fixed cap but applies medical necessity
Modifier rules: plans may or may not require AT, and some require their own authorization number
Documentation requests: plans often request notes before paying, so response time matters
Appeals: Medicare Advantage appeals go to the plan first, then to an independent review entity

Credentialing and enrollment

A chiropractor must be credentialed with each Medicare Advantage plan separately. Being enrolled in Medicare and having an NPI does not automatically put a provider in network. Credentialing takes weeks to months, and the paperwork a chiropractic practice needs grows with each plan, so start early and track expiration dates.

Billing mechanics

Medicare Advantage claims go to the plan, not to the Medicare Administrative Contractor, unless the plan uses a delegated arrangement. Eligibility, benefits, and authorization requirements all live with the plan. Build a one-page cheat sheet per payer with the portal, the authorization rule, and the appeal address.

Documentation CMS and OIG expect in the chiropractic record

CMS documentation expectations come from the coverage rule and the contractor articles that explain it. OIG documentation expectations come from audit findings and compliance guidance. They point at the same record elements, and a note built for one will usually satisfy the other.

The record must show the subluxation, the specific spinal level or levels, the method of manipulation, and the patient's response. It must also show that the care is active treatment, which is what the AT modifier certifies. If any of those pieces is missing, the claim is vulnerable.

The core elements

History, including the onset and the character of the complaint
Examination findings, including the segmental level of the subluxation
A diagnosis that matches the findings and the treated level
The treatment given, with the method and the levels adjusted
The patient's response and the plan for the next visit
A signature and a date on every entry

What auditors flag

Identical notes across dates, with no change in findings or response
Treatment levels that do not match the diagnosis or the CPT code
Missing or inconsistent AT modifier use
Care that continues past stabilization with no documented reason
Records that do not identify who performed and documented the service
Diagnosis codes that do not support the level treated

A worked example

A 54-year-old patient presents with three weeks of low back pain after lifting. The exam shows a subluxation at L4 and L5 with reduced range of motion. The chiropractor adjusts two regions, documents the change in range of motion, and sets a re-examination in four weeks. The claim is 98940 with AT and a matching diagnosis.

Four weeks later the findings have improved, so care continues. At week ten the findings are stable and the patient feels well between visits. The AT modifier comes off, and the patient is told maintenance care is not a Medicare benefit.

That sequence is defensible. The same ten visits with the same note copied each time are not.

Where coding and documentation meet

Diagnosis coding runs on the ICD-10-CM set, and the codes must describe the condition being treated at the level adjusted. Coders and billers should work from the note, not from the schedule. The ICD-10 | CMS pages carry the current code set and updates.

The CPT Code Information pages from the AMA carry the code descriptors and guidelines that drive 98940 through 98943. HCPCS covers the supplies and other items that occasionally appear on a chiropractic claim, and CMS publishes the Healthcare Common Procedure Coding System (HCPCS) | CMS files that list them.

Good notes also make month-end reporting cleaner. Practices that track denial rates and days in accounts receivable alongside clinical measures find problems faster, and the monthly KPIs worth watching include the AT modifier denial rate and the share of claims paid on first submission.

Maintenance care, medical necessity, and the limits of coverage

Maintenance care is the boundary line of the Medicare chiropractic benefit. CMS treats maintenance therapy as care given to maintain or prevent deterioration of a chronic condition, or to prevent a recurrence, once the patient's condition has stabilized. It is not a covered service.

The test is not how the patient feels on a given day. It is whether the condition is expected to improve with further treatment. If the answer is no, the care is maintenance, and the AT modifier does not belong on the claim.

Medical necessity for chiropractic care means the manipulation is reasonable and necessary for the diagnosis, meets accepted standards, and is not more than the patient needs. Contractors look for an expectation of improvement and a plan that reflects it.

Signs care has shifted to maintenance

The patient reports no change in symptoms over several visits
Objective findings are stable across re-examinations
Visits are scheduled at fixed intervals with no clinical trigger
The patient says the visits keep them feeling good rather than getting better
The treatment plan has no goals left to reach

How to handle the transition

Tell the patient in writing that further care is maintenance and not covered by Medicare. Offer a written notice and a private fee arrangement, following state and federal rules on beneficiary notices. Document the conversation. Then stop billing Medicare for those visits.

The difference between maintenance and a flare

A patient in maintenance care can still have a covered episode. A new injury or a documented flare that is expected to improve restarts active treatment. The record should show the new onset, the change in findings, and a new plan. Without that, the claim looks like maintenance with a different label.

Why this matters financially

Denials for maintenance care usually arrive long after the visits, which means repayment of money already spent. Practices that carry thin reserves feel it immediately, which is one reason a chiropractic practice plan belongs in the same conversation as clinical documentation. Set aside a reserve for potential recoupment rather than treating every collected dollar as profit.

Coding chiropractic claims with CPT and HCPCS for Medicare payers

Coding for Medicare chiropractic claims is narrow by design. The spinal manipulation codes are the core, and the AT modifier is the flag that makes them payable. Everything else on the claim must be justified or left off.

Evaluation and management codes may be billed on the same day as a manipulation when the evaluation is significant and separately identifiable. The note must support both services, and the documentation cannot be a single blended paragraph. If the evaluation is routine and part of the manipulation visit, do not bill it separately.

HCPCS codes apply to supplies and equipment, not to the manipulation itself. Orthopedic braces, pillows, and similar items may have HCPCS codes, but Medicare coverage for them is limited and often falls under a different benefit with its own rules. Check coverage before dispensing.

A clean claim checklist

Patient is enrolled and eligible on the date of service
Plan type confirmed: Original Medicare or Medicare Advantage
Diagnosis codes match the levels treated and the note
CPT code matches the number of spinal regions treated
AT modifier present when the care is active treatment
Evaluation and management code supported separately, if billed
Advance beneficiary notice on file where non-covered care is expected
Note signed and dated by the treating chiropractor

Common coding errors

Billing 98942 when the note supports three regions is an upcoding error. Billing 98943 for an extremity adjustment on a Medicare claim is a coverage error. Adding AT to a maintenance visit is a false claim. Each of these is avoidable with a second look before submission.

Modifiers beyond AT

Some contractors and plans ask for modifiers that describe the service setting or a reduced service. Use them only when the payer's policy calls for them. A modifier applied without a documented reason creates a mismatch between the claim and the note.

Keeping the codes current

The code sets change every year. Assign one person to review the annual updates to CPT, HCPCS, and ICD-10-CM before January 1, and update the fee schedule and the claim templates at the same time. Written document chiropractic practice service standards that include coding rules keep the whole team on the same page when staff turn over.

Audit exposure: what the OIG Work Plan flags for chiropractic billing

The OIG Work Plan is the list of audit targets the Office of Inspector General intends to review. Chiropractic services have appeared on it repeatedly, usually focused on whether Medicare paid for maintenance therapy billed as active treatment.

The Work Plan | Office of Inspector General | Government Oversight | U.S. Department of Health and Human Services is public, and reading it is a cheap way to see where contractors will look next.

Audits typically start with data analysis. The OIG compares the number of AT claims per beneficiary, the duration of care, and the pattern of visits across providers. Outliers get requests for records. From there the review is a document-by-document judgment about whether each visit was active treatment.

What triggers a review

A high volume of 98941 and 98942 claims relative to peers
Long courses of care with no gap or re-examination
The same note text across many dates
AT modifier use on nearly every claim for every patient
Diagnosis codes that do not change as the patient improves

What happens if the OIG finds a problem

The result is usually a demand for repayment, and in serious cases a referral for civil or administrative action. Providers can reduce exposure by running their own reviews first. Pull ten records a month, score them against the coverage rule, and fix what fails.

The OIG's physician education materials, including A Roadmap for New Physicians | Office of Inspector General | Government Oversight | U.S. Department of Health and Human Services, explain the compliance principles that apply to chiropractors as suppliers, including the rules on billing for services that were not medically necessary.

Building a compliance routine

Audit a sample of Medicare claims every month
Track denials by reason code and fix the cause, not just the claim
Train new staff on the AT modifier rule before they touch a claim
Keep a written policy on maintenance care and beneficiary notices
Review the OIG Work Plan and contractor articles each year

The cost of getting it wrong

A repayment demand can cover three years of claims. For a practice billing Medicare steadily, that number can exceed a year of profit. The defense is not a better appeal. It is a record that shows, visit by visit, that the patient was improving and the care was active.

Common questions

Does Medicare cover chiropractic care at all? Yes, but only manual manipulation of the spine to correct a subluxation, and only when the care is active treatment. Exams, imaging, and modalities are excluded from the benefit.

When do I use the AT modifier? Use AT on the spinal manipulation code when the care is active treatment. Leave it off when the patient has reached maximum therapeutic benefit and is in maintenance care.

Can I bill Medicare for maintenance visits? No. Maintenance care is not a covered benefit. Bill the patient directly under a private arrangement, with a written notice and a note documenting the conversation.

How is Medicare Advantage different from Original Medicare? Medicare Advantage plans may cover more services, such as maintenance visits or exams, and may require prior authorization. Check each plan's provider manual and evidence of coverage.

How long should I keep chiropractic records? Follow state law and payer requirements, and keep Medicare records at least as long as the state mandates. Many practices keep them longer because audit lookback periods can run several years.

What is the biggest audit risk in chiropractic billing? Billing maintenance care with the AT modifier, and using identical notes across dates. Both suggest the care was not active treatment, which puts the whole claim at risk.