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Modifiers are two-character alpha and/or numeric designations appended to Current Procedural Terminology (CPT®) and Healthcare Common Procedure Coding System (HCPCS) codes to provide additional information about a reported service or procedure. Modifiers communicate that a service was performed under specific circumstances without changing the definition of the underlying CPT or HCPCS code.
Accurate modifier selection is essential for compliant coding and reimbursement. Before appending a modifier, providers should verify that its use is supported by the clinical circumstances, documented in the medical record, and recognized by the applicable payer. When multiple modifiers are reported on the same procedure code, payment-affecting modifiers should be listed first, followed by informational modifiers. For example, modifier 26 (Professional Component) should be reported before modifier LT (Left Side).
Modifiers should be used to bypass a procedure-to-procedure (PTP) edit only when the National Correct Coding Initiative (NCCI) edit includes a modifier indicator of “1” and the medical record clearly supports that the services were distinct and separately reportable. Determining whether services qualify as separate can be challenging, particularly because Centers for Medicare & Medicaid Services (CMS) guidance may differ from CPT coding guidance.
To support compliant coding, providers should consult both CPT coding guidelines and the CMS NCCI Policy Manual.¹ Chapter 1 outlines the general correct coding policies that serve as the foundation for NCCI edits. For oncology practices, Chapter 11 provides specific guidance on chemotherapy administration coding, including examples of circumstances in which overriding an NCCI edit with an appropriate modifier may be justified.
For example: CPT codes 96360, 96365, 96374, 96409, and 96413 describe “initial” service codes. For a patient encounter, only one “initial” service code may be reported unless it is medically reasonable and necessary that the drug or substance administrations occur at separate intravenous access sites. To report two different “initial” service codes, use NCCI PTP-associated modifiers.
Among the modifiers used in oncology, modifier 59 (Distinct Procedural Service) is one of the most frequently reported and one of the most misused. Inappropriate use of modifier 59 is a recurring focus of payer audits and compliance reviews, making it essential that providers understand when its use is supported.
The CMS Medicare Learning Network publication Proper Use of Modifiers 59, XE, XP, XS, & XU explains the differences between the CPT guidance and CMS policy regarding modifier 59.² Under CMS guidelines, modifier 59 may be used to override an NCCI PTP edit only when the documentation demonstrates that the services were distinct because they were performed during a separate encounter or session, involved a different procedure, a different anatomic site or organ system, or a separate lesion.
CMS generally does not consider it appropriate to bypass an NCCI edit solely because two different procedures were performed during the same patient encounter at the same anatomic site. Exceptions to this policy are outlined in the CMS NCCI Policy Manual, including specific chemotherapy administration scenarios addressed in Chapter 11.
Use of modifier 59 directly affects reimbursement and is frequently reviewed during audits. Providers should ensure that its use is supported by complete medical record documentation and consistent with both CPT and CMS guidance.
In addition to modifier 59, oncology providers commonly append modifiers to communicate circumstances that affect coding and reimbursement, including:
Common Modifier Applications in Oncology
The following sections outline common circumstances in which modifiers are used in oncology coding and provide guidance on compliant reporting. Because modifier requirements vary by payer, providers should verify payer-specific billing instructions in addition to following CPT, HCPCS, and CMS guidelines.
Professional and Technical Components (Modifiers 26 and TC)
In radiation oncology, many diagnostic and therapeutic services consist of both a professional and a technical component. When these components are billed separately, modifier 26 (Professional Component) is appended to report the physician’s interpretation and professional work, while modifier TC (Technical Component) is appended when billing only the technical portion of the service, including equipment, supplies, and clinical staff resources. Providers should ensure the appropriate component is billed based on the services actually furnished and payer requirements.
Multiple Procedures (Modifier 51)
Modifier 51 (Multiple Procedures) was originally developed to identify secondary procedures performed during the same patient encounter. Historically, reimbursement for the lower-valued procedure was reduced because many practice expenses were shared between procedures. Today, most payers automatically identify multiple procedure discounts through claims processing systems. As a result, modifier 51 generally should not be appended unless specifically required by the payer.
Distinct Procedural Services (Modifier 59 and XE, XS, XP, XU)
Modifier 59 (Distinct Procedural Service) is used to identify procedures or services that are not normally reported together but are separately reportable under the circumstances. Appropriate use may include services performed on or during:
Modifier 59 should be used only when no more specific modifier accurately describes the circumstances. Whenever appropriate, the following HCPCS Level II modifiers should be reported instead:
CMS created the X modifiers to improve coding specificity and reduce inappropriate use of modifier 59. Medicare Administrative Contractors may require the use of these modifiers instead of modifier 59 when warranted.
Bilateral Procedures
Bilateral services are frequently reported for imaging studies but may apply to other oncology services as well. Depending on payer requirements, bilateral procedures may be reported by:
Repeat Procedures (Modifiers 76 and 77)
Modifiers 76 (Repeat Procedure by Same Physician) and 77 (Repeat Procedure by Another Physician) identify services repeated after completion of the original procedure. In radiation oncology, this commonly occurs when a patient receives an external beam radiation treatment in the morning and returns several hours later for a medically necessary second treatment on the same day. The initial treatment is reported without a modifier, while the repeat treatment is reported with modifier 76 or modifier 77, as appropriate. Documentation should clearly support the medical necessity for the repeat service.
Single-Dose Drug and Biological Modifiers (JW and JZ)
CMS requires reporting of discarded amounts from single-dose containers when billing Medicare Part B drugs and biologics.
When a portion of a single-dose vial is administered and the remainder is discarded, providers should report:
Modifier JW is reported only for the discarded amount. It should not be used when the administered dose is less than one billing unit or when the billing unit equals or exceeds the total amount administered and discarded.
Modifier JZ must be appended when no amount is discarded from a single-dose vial or package. CMS requires the appropriate use of JW or JZ modifiers on applicable claims. Claims missing the required modifier may be returned as unprocessable.
CMS publishes educational resources and maintains a list of HCPCS codes commonly associated with single-dose containers. Although the list is not exhaustive, it is updated periodically and should be reviewed regularly to support compliant reporting.
Evaluation and Management Services Reported with Procedures (Modifier 25)
Oncology providers frequently perform E/M services on the same date as procedures, such as bone marrow biopsies, chemotherapy administration, or other therapeutic services. When the patient visit is significant and separately identifiable from the procedure, modifier 25 should be appended to the E/M service. Modifier 25 indicates that the physician performed medically necessary work beyond the evaluation normally included before or after the procedure. The additional work must be clearly documented in the medical record.
The E/M service may address the same diagnosis as the procedure; separate diagnosis codes are not required under CPT guidelines. However, when separate diagnoses exist, they may further support the medical necessity of the independently reportable services. When considering modifier 25, providers should remember:
Appropriate modifier selection, supported by complete documentation and adherence to payer-specific requirements, remains one of the most effective ways to ensure compliant billing, reduce claim denials, and minimize audit risk in oncology practices.
Teri Bedard, BA, RT(R)(T)(ARRT), CPC, is Executive Director of Health Policy & Reimbursement at Revenue Cycle Coding Strategies in Des Moines, Iowa.
References
At the 2026 ASCO Annual Meeting, the Louisiana Oncology Society received the ASCO Jeffrey C Ward Affiliate Advocacy Award for advancing critical advocacy priorities that have translated into meaningful legislative victories. The Iowa Oncology Society and Washington State Medical Oncology Society were also recognized for their advocacy efforts in 2025 at the meeting, receiving second place awards.
