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    v1.0.28
    OpenPayerBilling CodesMiscellaneous Medical ServicesHCPCS hcpcs-m0243-casirivimab-imdevimab-infusion-injection-monitoring
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    HCPCS Level II M0243: Casirivimab and Imdevimab Infusion or Injection

    HCPCS Level II code M0243 describes an intravenous infusion or subcutaneous injection of casirivimab and imdevimab, including the administration procedure and post-administration monitoring; service type is therapeutic monoclonal antibody administration and the typical site of service is an outpatient infusion clinic, physician office, or ambulatory care setting where infusions or injections and observation are provided.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A 68-year-old patient with multiple comorbidities (type 2 diabetes, chronic obstructive pulmonary disease, and hypertension) presents to an outpatient infusion clinic after testing positive for SARS-CoV-2 and meeting high-risk criteria for progression to severe COVID-19. The clinician documents indication for monoclonal antibody therapy and orders M0243 for administration of casirivimab and imdevimab via intravenous infusion with post-administration monitoring.

    The clinical workflow: the patient is pre-screened by nursing for allergies and vital-sign stability, consent is obtained, and baseline vitals are recorded. A pharmacy prepares the monoclonal antibody product per manufacturer guidance. An infusion nurse places an IV, administers the infusion per protocol, observes for infusion-related reactions during and after administration, documents start and stop times, and provides discharge instructions. If an adverse reaction occurs, the nurse initiates emergency protocols, documents interventions, and may bill appropriate modifiers if services are unusual or discontinued.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    96365Intravenous infusion, therapeutic, prophylactic, or diagnostic; initial, up to 1 hourUsed when infusion of casirivimab and imdevimab is billed as an infusion service in addition to or instead of HCPCS drug code, for initial infusion time reporting.
    96366Intravenous infusion, each additional hour (List separately in addition to code for primary procedure)Billed when infusion time exceeds the initial hour and additional hourly reporting is required.
    96360Intravenous infusion, hydration; initial, 31 minutes to 1 hourMay be billed if concurrent hydration is provided during the monoclonal antibody infusion.
    36415Collection of venous blood by venipuncturePerformed for pre-infusion testing (e.g., baseline labs) and billed when applicable.
    99214Office or other outpatient visit for an established patient, moderate complexityUsed for the evaluation and management visit that results in the order for monoclonal antibody therapy when a separate E/M is documented.

    Related Modifiers

    8 rows

    ModifierDescriptionWhen to Use
    22Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…
    23Modifier -23 (Unusual Anesthesia) is used on anesthesia service CPT codes when a procedure that normally requires no anesthesia or only local anesthesia must be performed under general anesthesia…- Use modifier -23 only on anesthesia CPT codes (00100–01999) when a procedure that normally requires no anesthesia or only local anesthesia must be performed under general anesthesia because of…
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    54Modifier ‑54 (“Surgical care only”) is appended to a CPT surgical procedure when the reporting surgeon performs the intraoperative (surgical) component but does not furnish the preoperative and/or…- Use modifier -54 when the reporting surgeon provided only the intraoperative (surgical) component of a procedure and preoperative and/or postoperative management has been or will be provided by…
    55Modifier –55 indicates the billing provider furnished only postoperative management for a procedure that has a global surgical period. According to AAPC, this modifier is appended to the same CPT…- Use modifier -55 when billing the same CPT surgical code that has a 10- or 90-day global period and you, as a provider other than the original surgeon, furnished ONLY postoperative management (no…
    62Modifier 62 indicates that two surgeons function as co‑surgeons, each performing distinct parts of the same primary surgical procedure. It is appended to the primary procedure code (and any…- Use modifier -62 when two surgeons act as co‑surgeons (both primary surgeons) on a single definitive primary procedure, each performing distinct parts of the same surgical procedure (append -62 to…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    207Q00000XFamily Medicine PhysicianFamily Medicine is the medical specialty which is concerned with the total health care of the individual and the family. It is the specialty in breadt…
    207R00000XInternal Medicine PhysicianA physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults…
    363L00000XNurse Practitioner(1) A registered nurse provider with a graduate degree in nursing prepared for advanced practice involving independent and interdependent decision mak…
    207K00000XAllergy & Immunology PhysicianAn allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Select…
    103TF0200XForensic PsychologistA psychologist whose specialty is characterized by activities primarily intended to provide professional psychological expertise within the judicial a…
    224ZF0002XFeeding, Eating & Swallowing Occupational Therapy AssistantOccupational therapy assistants provide environmental modifications under the supervision of an occupational therapist. OTAs develop and implement an…
    207QG0300XGeriatric Medicine (Family Medicine) PhysicianA family medicine physician with special knowledge of the aging process and special skills in the diagnostic, therapeutic, preventive and rehabilitati…
    261QA0006XAmbulatory Fertility FacilityA fertility facility, which may be licensed, registered, or certified in some states, that is not hospital-based, where services are provided at a fi…

    Related Codes

    HCPCS-M0075-CELLULAR-THERAPY-PROCESSING-PROVISION

    HCPCS Level II M0075: Cellular Therapy

    HCPCS-M0076-PROLOTHERAPY-INJECTION-THERAPY

    HCPCS Level II M0076: Prolotherapy

    HCPCS-M0100-INTRAGASTRIC-HYPOTHERMIA-GASTRIC-FREEZING

    HCPCS Level II M0100: Intragastric Hypothermia (Gastric Freezing)

    HCPCS-M0201-IN-HOME-VACCINE-ADMINISTRATION

    HCPCS Level II M0201: In-Home Vaccine Administration

    HCPCS-M0220-TIXAGEVIMAB-CILGAVIMAB-PRE-EXPOSURE-PROPHYLAXIS

    HCPCS Level II M0220: Tixagevimab and Cilgavimab Pre-Exposure Prophylaxis

    HCPCS-M0221-TIXAGEVIMAB-CILGAVIMAB-PRE-EXPOSURE-PROPHYLAXIS-HOME-ADMINISTRATION

    HCPCS M0221: Tixagevimab and Cilgavimab Pre-Exposure Prophylaxis

    HCPCS-M0222-BEBTELOVIMAB-INTRAVENOUS-INJECTION-MONITORING

    HCPCS Level II M0222: Bebtelovimab Intravenous Injection with Monitoring

    HCPCS-M0223-BEBTELOVIMAB-INTRAVENOUS-INJECTION-HOME-MONITORING

    HCPCS M0223: Intravenous Bebtelovimab with Home Monitoring

    HCPCS-M0224-PEMIVIBART-PRE-EXPOSURE-PROPHYLAXIS-INFUSION

    HCPCS M0224: Pemivibart Intravenous Infusion for Pre-Exposure Prophylaxis

    HCPCS-M0233-TOCILIZUMAB-INFUSION-COVID19-HOSPITALIZED-ADULTS

    HCPCS Level II M0233: Tocilizumab-aazg IV Infusion, First Dose

    Showing 1–10 of 27

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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