Introduction

Chiropractic practices deal with several billing and coding requirements when submitting claims to insurance companies. From selecting the correct CPT codes to understanding payer-specific guidelines, every step plays an important role in receiving accurate and timely reimbursement. One area that deserves special attention is the proper use of billing modifiers.

Chiropractic billing modifiers provide additional information about the services performed during a patient visit. They help insurance companies understand the circumstances surrounding a procedure, distinguish between different types of services, and determine whether a claim meets coverage requirements.

Even a small mistake in modifier selection can create billing problems. Claims may be denied, payments may be delayed, and billing teams may spend additional time correcting and resubmitting claims.

For chiropractic providers, understanding commonly used modifiers is essential for maintaining an efficient revenue cycle. This guide explains the most important chiropractic billing modifiers, their purposes, Medicare requirements, common mistakes, and practical strategies for improving claim accuracy in 2026.

1.   What Are Chiropractic Billing Modifiers?

Chiropractic billing modifiers are two-character codes added to certain CPT or HCPCS procedure codes to provide additional information about a service.

A procedure code generally explains what service was performed, while a modifier provides more details about how or under what circumstances that service was delivered.

For example, a chiropractor may perform spinal manipulation to address a patient’s documented spinal condition. When billing Medicare for an eligible manipulation service, the AT modifier may be required to identify active treatment.

Modifiers help insurance companies evaluate claims more accurately. However, they do not independently establish medical necessity or guarantee payment. The service must still meet the applicable coverage requirements, documentation standards, and payer policies.

In chiropractic billing, modifiers are particularly important when dealing with Medicare-covered spinal manipulation, advance beneficiary notices, distinct procedures, and services performed under different treatment plans.

2. Why Are Modifiers Important in Chiropractic Medical Billing?

Accurate modifier reporting is an important part of clean claim submission. Chiropractic services may involve different treatment approaches, coverage limitations, and insurance requirements. Modifiers help communicate the relevant details to the payer.

Here are several reasons why proper modifier usage matters:

Improved Claim Accuracy: Correct modifiers provide additional information about the reported service and help reduce coding-related errors.

Better Reimbursement Processing: When a claim contains accurate procedure codes, modifiers, and supporting documentation, the payer can evaluate the service more appropriately.

Reduced Claim Denials: Incorrect or missing modifiers can cause claim rejections or denials, depending on the payer’s billing requirements.

Clearer Medical Documentation: Appropriate modifier reporting helps connect the billed service with the treatment provided and the circumstances documented in the patient’s record.

Improved Compliance: Following Medicare and commercial insurance guidelines helps chiropractic practices maintain accurate billing records and reduce unnecessary compliance risks.

Ultimately, modifiers are not simply extra characters added to a claim. They are an important part of communicating accurate billing information.

3. Commonly Used Modifiers in Chiropractic Billing

Different modifiers may apply to chiropractic-related services depending on the procedure, payer, and circumstances of the encounter. Understanding their definitions and limitations can help billing teams avoid incorrect reporting.

AT Modifier – Active Treatment

The AT modifier identifies active treatment when reporting eligible chiropractic manipulative treatment services to Medicare.

It is particularly important because Medicare generally distinguishes between active or corrective treatment and maintenance care.

The modifier may be appropriate when a chiropractor is actively treating a documented spinal subluxation and the service meets Medicare coverage requirements.

However, the AT modifier should not be reported automatically on every chiropractic claim. The provider must establish that the service represents active treatment rather than maintenance care.

GA Modifier – Waiver of Liability Statement on File

The GA modifier indicates that an appropriate waiver of liability statement, commonly known as an Advance Beneficiary Notice (ABN), has been issued as required by applicable Medicare rules.

Chiropractors may encounter situations where a service is expected to be denied because it does not meet Medicare coverage requirements.

When the ABN requirements are satisfied, the GA modifier may be used in accordance with Medicare billing instructions.

An ABN must be handled correctly. Simply adding GA to a claim does not replace the required notice process or guarantee that a beneficiary will be financially responsible.

GZ Modifier – Expected Denial Without an ABN

The GZ modifier indicates that an item or service is expected to be denied as not reasonable and necessary, but a required ABN was not obtained.

This modifier helps communicate the circumstances of the expected denial.

For chiropractic practices, understanding the difference between GA and GZ is especially important when dealing with services that may fall outside Medicare coverage.

Billing teams should follow current Medicare instructions when determining whether GZ is appropriate.

GP Modifier – Services Delivered Under a Physical Therapy Plan of Care

The GP modifier identifies services delivered under an outpatient physical therapy plan of care.

It may be relevant when a chiropractic practice also provides qualifying physical therapy services.

However, GP is not a general-purpose chiropractic modifier. It should only be reported when the service and applicable billing rules support its use.

Chiropractic manipulation codes should not automatically receive GP simply because the provider is a chiropractor.

Modifier 59 – Distinct Procedural Service

Modifier 59 identifies a distinct procedural service when the circumstances satisfy the applicable coding requirements.

It may be relevant when two procedures are performed during the same encounter but are sufficiently distinct to qualify for separate reporting.

For example, a provider may perform two services that are separately identifiable under the applicable coding rules. If an NCCI edit applies, modifier 59 or an appropriate more specific X modifier may be permitted when the documentation supports a distinct service.

Modifier 59 should never be used simply to bypass an insurance edit or obtain additional reimbursement.

Modifier 25 – Significant, Separately Identifiable Evaluation and Management Service

Modifier 25 is used when a provider performs a significant, separately identifiable evaluation and management (E/M) service on the same day as another procedure or service.

For example, a patient may receive a chiropractic manipulation and also require a separately documented evaluation of a new or unrelated complaint.

When the E/M service is significant and separately identifiable beyond the usual work associated with the procedure, modifier 25 may be appropriate if payer requirements are met.

Routine evaluation and work normally included in the procedure do not automatically justify modifier 25.

4. Understanding the AT Modifier in Chiropractic Billing

The AT modifier deserves particular attention because of its importance in Medicare chiropractic billing.

Medicare Part B generally covers manual manipulation of the spine to correct a subluxation when the applicable coverage requirements are met. The AT modifier identifies that the chiropractic manipulation is being provided as active treatment.

When Should Chiropractors Use the AT Modifier?

The AT modifier may be appropriate when:

• The patient has a documented spinal subluxation.
• The chiropractor is providing active or corrective treatment.
• The treatment meets Medicare coverage requirements.
• The patient’s medical record supports the need for the service.
• The billed manipulation code and documentation are consistent with the service performed.

Active Treatment vs. Maintenance Care

Understanding the difference between active treatment and maintenance care is essential.

Active Treatment: Treatment intended to correct or improve a documented spinal condition. The provider is working toward measurable clinical improvement or functional recovery.

Maintenance Care: Treatment intended to maintain the patient’s current condition, prevent future deterioration, or provide ongoing supportive care after the active treatment goals have been reached.

Medicare generally does not cover chiropractic maintenance therapy.

For example, consider a patient who visits a chiropractor because of a documented spinal condition. The chiropractor develops a treatment plan and performs spinal manipulation to improve the patient’s condition. If all Medicare coverage requirements are met, the AT modifier may be appropriate.

Now consider a patient whose condition has stabilized and who continues receiving routine manipulation only to maintain the current level of function. This is generally considered maintenance care and is not covered by Medicare.

The provider must make the distinction based on the patient’s actual condition, treatment goals, and clinical documentation rather than simply choosing a modifier to obtain payment.

Documentation Requirements for AT Modifier Billing

Accurate documentation is essential when submitting claims with the AT modifier.

A chiropractic medical record should support:

The patient’s relevant history and presenting complaints.

The spinal condition or subluxation being treated.

Appropriate examination findings.

The treatment plan and clinical goals.

The spinal regions manipulated.

The patient’s response to treatment.

Progress toward established treatment goals.

Complete documentation helps demonstrate that the service was medically necessary and consistent with Medicare coverage requirements.

5. Common Chiropractic CPT Codes and Modifier Considerations

Chiropractic providers commonly use CPT codes 98940, 98941, and 98942 to report spinal chiropractic manipulative treatment.

The following table provides an overview of commonly used codes:

CPT Code	Description
98940	Chiropractic manipulative treatment involving 1–2 spinal regions
98941	Chiropractic manipulative treatment involving 3–4 spinal regions
98942	Chiropractic manipulative treatment involving 5 spinal regions
98943	Chiropractic manipulative treatment involving extraspinal regions

Understanding the Coding Requirements

Each CPT code represents a different scope of chiropractic manipulation.

For Medicare-covered spinal manipulation, the AT modifier may be required when the service represents active treatment and meets coverage requirements.

However, CPT code selection and modifier assignment are separate decisions. The provider must report the correct code based on the regions actually treated and apply modifiers only when supported by the relevant guidelines.

For example:

• A patient receives manipulation involving two spinal regions. The provider evaluates the service and determines that CPT 98940 accurately describes the procedure.
• Another patient receives manipulation involving four spinal regions. CPT 98941 may be appropriate.
• A patient receives manipulation involving five spinal regions. CPT 98942 may be applicable.

These examples explain code selection only. They do not automatically establish Medicare coverage or determine which modifier must be reported.

It is also important to understand that CPT 98943 describes extraspinal manipulation and should not be assumed to have the same Medicare coverage as spinal manipulation codes.

6. Medicare Chiropractic Billing Modifier Guidelines

Medicare has specific requirements for chiropractic services, particularly when determining whether spinal manipulation qualifies for coverage.

Billing teams must understand these requirements before submitting claims.

Medicare Coverage for Chiropractic Manipulation

Medicare Part B generally covers manual manipulation of the spine when it is performed to correct a subluxation and meets the applicable coverage requirements.

Other services that may be provided in a chiropractic office are not automatically covered simply because they are part of the patient’s treatment plan.

Importance of the AT Modifier

The AT modifier identifies active treatment for eligible chiropractic manipulation services.

When the modifier is required, omitting it may result in a claim denial or incorrect processing.

However, reporting AT on maintenance services does not make those services Medicare-covered.

Understanding ABNs

An Advance Beneficiary Notice of Noncoverage (ABN) is a written notice used in certain Original Medicare situations when a provider believes Medicare may not cover a service.

The notice informs the beneficiary about the expected noncoverage and potential financial responsibility before the service is provided.

Chiropractic practices should understand when an ABN is required, how to complete it, and how to retain the necessary documentation.

GA and GZ Modifier Requirements

The GA modifier is generally used when a valid ABN is on file and the applicable Medicare requirements are satisfied.

The GZ modifier is generally used when a service is expected to be denied as not reasonable and necessary and a required ABN was not obtained.

These modifiers communicate different circumstances and should not be used interchangeably.

Documentation and Medical Necessity

Medicare billing requires appropriate documentation to support covered chiropractic manipulation.

The patient’s medical record should clearly explain the condition being treated, examination findings, treatment plan, and services performed.

Providers should also review applicable Medicare Administrative Contractor (MAC) guidance because billing instructions and coverage details may vary by jurisdiction.

7. Common Chiropractic Billing Modifier Mistakes

Even experienced billing professionals can make mistakes when working with chiropractic claims. These errors may lead to denials, payment delays, and additional administrative work.

Here are some common issues to avoid.

1. Incorrect Use of the AT Modifier

One common mistake is reporting AT on every chiropractic manipulation claim without determining whether the service represents active treatment.

The modifier should only be reported when the applicable Medicare requirements are satisfied.

2. Confusing Active Treatment With Maintenance Care

Active treatment and maintenance care have different coverage implications under Medicare.

Reporting maintenance services as active treatment can create compliance concerns and potential payment problems.

3. Incorrect GA Modifier Reporting

The GA modifier should not be used simply because a service is expected to be denied.

The required ABN process must be completed correctly when applicable.

4. Using GZ Without Understanding the Requirements

Billing teams sometimes confuse GA and GZ.

Because these modifiers communicate different ABN circumstances, incorrect reporting can result in claim processing problems.

5. Overusing Modifier 59

Modifier 59 should only be applied when the services meet the criteria for distinct procedural reporting.

Using it without supporting documentation or simply to bypass an NCCI edit can create compliance risks.

6. Applying GP to Every Chiropractic Service

The GP modifier is associated with services delivered under an outpatient physical therapy plan of care. It is not automatically required for chiropractic manipulation.

7. Ignoring Insurance-Specific Requirements

Medicare, Medicare Advantage plans, and commercial insurance companies may have different billing requirements.

Using the same modifier combinations for every payer without checking their policies can result in avoidable denials.

8. How Incorrect Modifiers Affect Chiropractic Reimbursement

Modifier errors can affect more than a single claim. Repeated billing mistakes may create financial challenges for an entire chiropractic practice.

Here are some potential consequences:

Claim Denials: Incorrect or missing modifiers may cause insurance companies to deny claims or request additional information.

Delayed Payments: Denied claims often require investigation, correction, and resubmission, which can extend the reimbursement process.

Increased Accounts Receivable: Unresolved claims remain in accounts receivable and may affect the practice’s cash flow.

Additional Administrative Costs: Billing staff must spend extra time reviewing, correcting, and appealing claims.

Compliance Risks: Inaccurate modifier reporting may result in payer audits, recoupment requests, or other compliance concerns.

Reduced Revenue Performance: When billing errors occur frequently, the practice may struggle to collect the full amount it is eligible to receive.

A consistent billing review process can help identify problems before claims are submitted.

9. Best Practices for Accurate Chiropractic Modifier Billing

Maintaining accurate chiropractic billing requires more than selecting the correct CPT code. Practices should establish a reliable process for reviewing documentation, verifying coverage, and checking modifier requirements.

Here are some practical ways to improve billing accuracy.

Verify Insurance Coverage

Before providing services, verify the patient’s insurance coverage and understand the applicable chiropractic benefits, limitations, and authorization requirements.

Review Documentation Carefully

Make sure the medical record supports the service performed and the modifiers reported on the claim.

Understand Payer-Specific Rules

Do not assume that Medicare and commercial insurance companies follow identical modifier requirements. Review current payer policies before submitting claims.

Use Correct CPT Codes

Select procedure codes based on the actual service and spinal regions treated. Incorrect code selection can create problems even when the modifier is correct.

Monitor Claim Denials

Review denied chiropractic claims regularly to identify recurring modifier-related issues. Tracking denial reasons can help billing teams correct problems at their source.

Perform Regular Billing Audits

Periodic claim audits can identify incorrect modifier combinations, missing documentation, and inconsistent billing practices.

Train Billing Staff

Provide ongoing training to coding and billing professionals so they remain familiar with Medicare updates, payer policies, and applicable coding guidelines.

Follow Current Coding Updates

CPT, HCPCS, Medicare, and payer requirements can change. Practices should use current-year coding resources rather than relying on outdated billing references.

10. How EMBS Helps Chiropractic Practices Improve Their Billing Process

Managing chiropractic billing while focusing on patient care can become challenging. Providers must balance clinical responsibilities with insurance verification, coding accuracy, claim submission, payment posting, and denial follow-up.

This is where professional medical billing support can make a difference.

Expert Medical Billing Services (EMBS) provides medical billing and revenue cycle management solutions designed to help healthcare practices manage their billing operations more efficiently.

Our services can support chiropractic practices through:

• Medical Coding: Accurate code selection based on provider documentation and applicable coding guidelines.
• Insurance Verification: Checking patient eligibility and benefits before services are provided.
• Charge Entry: Reviewing and entering charges accurately to support clean claim submission.
• Claim Submission: Preparing and submitting claims according to payer requirements.
• Denial Management: Identifying denial reasons and working on appropriate corrections and appeals.
• Accounts Receivable Management: Following up on outstanding claims and unpaid balances.
• Payment Posting: Recording insurance payments and adjustments accurately.
• Revenue Cycle Management: Supporting the billing process from patient registration through final payment.

At EMBS, our goal is to help healthcare providers reduce administrative billing challenges, improve claim accuracy, and maintain a more organized revenue cycle.

11. Frequently Asked Questions About Chiropractic Billing Modifiers

1. What are chiropractic billing modifiers?

Chiropractic billing modifiers are two-character codes added to procedure codes when appropriate to provide additional information about the service performed. They help insurance companies understand specific billing circumstances and process claims according to applicable guidelines.

2. What is the AT modifier in chiropractic billing?

The AT modifier identifies active treatment when reporting eligible chiropractic spinal manipulation services to Medicare. It helps distinguish active or corrective treatment from maintenance care.

3. When should chiropractors use the GA modifier?

The GA modifier is generally used when an appropriate ABN has been issued and the applicable Medicare requirements are satisfied. It communicates that a waiver of liability statement is on file.

4. What is the difference between GA and GZ modifiers?

GA indicates that an appropriate ABN is on file. GZ indicates that a service is expected to be denied as not reasonable and necessary, but a required ABN was not obtained.

5. Does Medicare require the AT modifier?

Medicare generally requires the AT modifier on claims for covered chiropractic spinal manipulation when the service represents active treatment. Providers should follow current Medicare billing instructions and applicable coverage policies.

6. Does Medicare cover chiropractic maintenance therapy?

Generally, no. Medicare does not cover chiropractic maintenance therapy. Coverage is limited to eligible spinal manipulation services performed to correct a subluxation when the applicable requirements are met.

7. What CPT codes are commonly used in chiropractic billing?

Common spinal chiropractic manipulation codes include 98940, 98941, and 98942. CPT 98943 describes extraspinal manipulation. Coverage and reporting requirements depend on the service and payer.

8. What happens when an incorrect modifier is submitted?

An incorrect modifier may result in a claim rejection, denial, delayed payment, or additional documentation requests. Repeated errors can also create compliance and reimbursement concerns.

9. Can multiple modifiers be reported on a chiropractic claim?

Multiple modifiers may be reported when the circumstances of the service and applicable coding rules support them. Each modifier must have a valid purpose and appropriate documentation.

10. How can chiropractic practices reduce billing denials?

Practices can reduce preventable billing denials by verifying insurance coverage, selecting accurate CPT codes, applying appropriate modifiers, maintaining complete documentation, reviewing payer policies, and following up on denied claims.

Conclusion

Accurate modifier reporting is an important part of successful chiropractic medical billing. Understanding modifiers such as AT, GA, GZ, GP, 59, and 25 helps billing professionals communicate services correctly and follow applicable insurance requirements.

However, selecting the right modifier is only one part of the process. Accurate CPT coding, complete clinical documentation, insurance verification, and consistent claim monitoring are equally important for maintaining an efficient revenue cycle.

Chiropractic practices that invest in accurate billing procedures can reduce preventable errors, improve claim management, and spend more time focusing on patient care.

Looking for reliable chiropractic medical billing support? Expert Medical Billing Services (EMBS) is here to help healthcare providers streamline billing operations, manage claim denials, improve accounts receivable follow-up, and strengthen revenue cycle performance.