Medicare Chiropractic Rules: AT Modifier, ABN, and PART Notes

The Only Chiropractic Services Medicare Covers: 98940, 98941, 98942

Medicare only considers spinal manipulation to correct a subluxation as a covered chiropractic service. This is true regardless of what else a chiropractor offers in the office. The official CPT codes are 98940 for one or two regions, 98941 for three or four regions, and 98942 for all five regions. These codes specifically describe manual manipulation of the spine. Even if a patient receives other services, only these codes are billable to Medicare by a chiropractor.

It does not matter if the patient has back pain, headaches, or another complaint. For Medicare, chiropractic coverage stops at spinal adjustment to treat a subluxation. Everything else, from exams to therapies, falls outside the scope of covered chiropractic services.

Keep reading: Inside a 24 Visit Low Back Care Plan, From Intake to Discharge

Why a Chiropractor Cannot Opt Out or Privately Contract

Unlike medical doctors, chiropractors are not allowed to opt out of Medicare or enter private contracts with Medicare beneficiaries for covered services. This rule is strict. If a patient has Medicare and the service is covered, the only choices are to submit the claim to Medicare or provide the service as non-assigned (with the patient paying up front for non-covered services).

This means that for spinal manipulation, a chiropractor cannot ask a Medicare patient to pay cash without first submitting the claim (assigned or non-assigned) and following all Medicare rules. It also means that non-covered services can be offered for cash, but the patient must know the difference, and the documentation must be clear about which services are covered and which are not.

The AT Modifier and the Line Between Active and Maintenance Care

The AT modifier tells Medicare that the spinal manipulation being billed is for active treatment, not maintenance. This modifier must be attached to the procedure code any time care is aimed at improving a clinical condition, such as reducing pain or restoring function. If the care is only supportive or intended to prevent recurrence, Medicare will not pay, and the AT modifier should not be used.

How Active Care Is Defined

Active care involves a specific treatment plan, with measurable goals and regular re-evaluation. The plan must address functional loss, pain, or documented subluxation, and it must be time-limited. If the patient is stable, has reached maximum medical improvement, or is receiving care solely to maintain current status, this is maintenance care, and Medicare will not reimburse for it.

Consequences of Using the AT Modifier Incorrectly

Using the AT modifier for maintenance care can trigger an audit. If Medicare determines that care was not active or medically necessary, the claim will be denied, and recoupment may be required. This is why the AT modifier should only be attached when the documentation supports active care, with clear goals and objective findings.

Keep reading: Visit Caps, Managed Networks, and the Shift to Cash Care Plans

When the ABN Becomes Mandatory and How GA Follows It

The Advance Beneficiary Notice (ABN) is required whenever a chiropractor believes Medicare may not pay for a service that would otherwise be covered. This usually comes up in two situations: when the service is maintenance care, or when the visit does not meet Medicare criteria for medical necessity. The ABN gives the patient official notice that Medicare is likely to deny the claim, and it allows the patient to decide whether to proceed with care and accept financial responsibility.

Timing and Delivery of the ABN

The ABN must be presented to the patient before the service is performed. It should be specific, listing the service and the reason Medicare may not pay. The patient chooses one of three options: receive the service and have it billed to Medicare, receive the service and not bill Medicare, or decline the service. The signed ABN must be kept in the patient's file.

Using GA When Billing

When an ABN is on file and the chiropractor is billing a service likely to be denied, the GA modifier is attached to the CPT code. This tells Medicare that the ABN process was followed, and responsibility can shift to the patient if the claim is denied. If no ABN is given and the claim is denied, the provider may not collect from the patient. Proper use of the ABN and GA modifier protects both the clinic and the patient from confusion and denied payments.

PART: Two of Four Findings, and Which Two Must Be There

Medicare requires documentation of subluxation for every covered adjustment. The PART system breaks this into four categories: Pain/tenderness, Asymmetry/misalignment, Range of motion abnormality, and Tissue/tone changes. At least two of these four must be documented at each visit, and one of them must be either Asymmetry/misalignment or Range of motion abnormality.

How to Document PART

Pain/tenderness can be recorded as patient-reported or provider-observed, such as point tenderness on palpation. Asymmetry/misalignment is noted by visual or palpatory findings, such as a rotated vertebra. Range of motion abnormality involves decreased, increased, or aberrant movement in the affected region. Tissue/tone changes can include swelling, muscle spasm, or changes in skin texture.

For Medicare compliance, a note stating only "pain" is not enough. There must be objective findings for at least two PART categories, and one must be either Asymmetry/misalignment or Range of motion abnormality. If these are not present, the visit does not meet Medicare's standard for a covered service.

See how CarePlanTrack handles this for chiropractic and manual therapy

What the Initial Note and Every Subsequent Note Must Contain

Medicare expects detailed documentation for every covered visit. The initial note must show a clear diagnosis of subluxation, how it was identified (with x-ray or physical exam), and a treatment plan. This plan should include the goals of care, frequency and duration of visits, and the expected outcome.

Initial Visit Requirements

• History of the present illness and any relevant past history
• Physical exam findings, including PART documentation
• Diagnosis of subluxation (by region and method of detection)
• Detailed treatment plan, with goals and expected duration

Subsequent Visit Requirements

• Documentation of progress toward the treatment goals
• Updated PART findings
• Any changes to the treatment plan

Every visit note must show why care is still active. If the notes repeat the same findings each time or fail to show change, auditors may conclude that the care is maintenance and deny payment. Detailed, individualized notes are critical for both compliance and reimbursement.

Non Covered Services Patients Still Ask For: Exams, X Rays, Modalities

Many patients expect a full range of services at their chiropractic visit, but Medicare does not pay for exams, x-rays ordered by a chiropractor, physical therapy modalities, or therapies such as ultrasound or electrical stimulation when performed by a chiropractor. These are considered non-covered regardless of diagnosis or necessity. The patient is responsible for payment.

It is important to explain to patients that their Medicare coverage does not extend to these services in a chiropractic setting. An ABN is not required for services that are never covered, but it is still good practice to obtain written acknowledgment from the patient. This can prevent misunderstandings and disputes about billing later.

When providing non-covered services, clear documentation is important. The record should show the service, the patient's acknowledgment of non-coverage, and the amount collected. This protects the clinic in the event of a patient complaint or audit.

Keeping the Treatment Plan Ready for a Records Request

Medicare contractors can request records at any time to check compliance. Most commonly, these requests focus on proving that care billed as active meets all requirements. The treatment plan should always be up to date, clearly marked in the record, and easy to produce if needed. It must show the diagnosis, goals, frequency and duration, and evidence of progress at each re-exam.

Missed visits, skipped re-exams, and lack of documentation are common reasons claims are denied or recouped. Clinics that track patient progress and stay on top of re-exam scheduling are more likely to pass an audit without issue. When care shifts from active to maintenance, the record should show this, and billing should stop using the AT modifier.

Many clinics now use tools designed for care plan tracking. These systems can help monitor visit counts, flag missed appointments, and prompt timely re-exams. Patient-facing progress updates and alerts can also improve communication and compliance. Solutions like these support proper record keeping and make it easier to meet Medicare's documentation demands.