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    v1.0.30
    OpenPayerBilling CodesTemporary National Codes (Non-Medicare)HCPCS hcpcs-s9559-home-interferon-injectable-therapy-per-diem
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    HCPCS Level II S9559: Home Injectable Therapy, Interferon

    HCPCS Level II code S9559 describes a per-diem home injectable therapy administrative bundle for interferon, covering professional pharmacy services, care coordination, supplies, equipment, and nursing-related administrative tasks; the service type is home infusion support / outpatient home injectable therapy and the typical site of service is the patient’s home (drug products and nursing visits are coded separately).

    For related coverage guidance, see recent payer policy updates: Ambulance and Medical Transport Services (Ground, Air and Water) Corporate Medical Policy, Emergency Air/Water Ambulance Services Medical Guideline, Non-Emergent Ambulance Services.

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    Clinical & Coding Specifications

    Clinical Context

    A home-based adult patient with relapsing-remitting multiple sclerosis is prescribed interferon beta therapy delivered via subcutaneous injection at home. The patient receives a per‑diem administrative service that covers medication management coordination, professional pharmacy services (education, adherence assessment), scheduling and oversight of nursing visits for injection instruction or observation, and provision of necessary disposables (syringes, sharps container, alcohol swabs). The clinical workflow begins with the prescriber writing the interferon order and documenting indication and dosing. The pharmacy or home infusion provider establishes prior authorization with the payer, performs patient education on self-injection technique, documents baseline adverse effect counseling, and arranges nursing visits when needed (initial home visit for teaching, periodic competency checks, and symptom monitoring). Clinical monitoring includes assessment of flu-like symptoms, injection site reactions, routine laboratory monitoring (CBC, liver function tests) per the prescriber’s protocol, and communication of abnormal results to the ordering clinician. Visits are coordinated with the drug and nursing claims: the per‑diem administrative code S9559 is billed for the ongoing home injectable therapy administrative services while the interferon drug and any nursing visit CPT/HCPCS are billed separately. Typical site of service is the patient’s residence (home health / home infusion setting). Typical payors include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, BUCA plans, and Medicare, each requiring documentation of medical necessity, prior authorization when applicable, and clear linkage between S9559 and the separately billed drug and nursing services.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    96372Therapeutic, prophylactic, or diagnostic injection (specify substance or drug); subcutaneous or intramuscularUsed when a clinician or nurse administers an interferon injection in the home setting; billed separate from the administrative per‑diem S9559
    99213Office or other outpatient visit for the evaluation and management of an established patient, typically 15 minutesUsed for periodic follow‑up visits (telehealth or in‑person) to assess therapy tolerance and lab review; billed separately from S9559
    99406Smoking and tobacco use cessation counseling visit, intermediate, greater than 3 minutes up to 10 minutesExample of ancillary counseling service that may be provided and billed separately when clinically relevant
    99091Collection and interpretation of physiologic data digitally stored and/or transmitted by the patient and/or caregiverMay apply when remote monitoring data related to therapy tolerability is collected and reported in addition to S9559
    G0490Home health partial hospitalization per day (note: example HCPCS/G code)

    Related Modifiers

    6 rows

    ModifierDescriptionWhen to Use
    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…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    76Modifier -76, Repeat Procedure or Service by Same Physician or Other Qualified Health Care Professional, is appended when the same provider performs an identical, medically necessary procedure or…- Use modifier -76 when the same physician or other qualified health care professional performs an identical procedure or service a second (or subsequent) time on the same date of service and the…
    77Modifier 77 indicates that a previously performed procedure or service was legitimately repeated by a different physician or other qualified health care professional. The AMA’s CPT definition…- Use modifier 77 when a basic procedure or service already performed is repeated by a different physician or other qualified health care professional (for example, a second provider independently…
    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…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    171400000X
    251B00000X
    208000000X
    207Q00000X
    207L00000X
    225XP0200X
    246X00000X
    163WP0808X

    Related Payer Policy Updates

    Specialty: Emergency & Medical Transportation1 / 3

    10 rows

    PolicyPayerEffective Date
    Ambulance and Medical Transport Services (Ground, Air and Water) Corporate Medical Policybcbsvermont2026-10-01
    Emergency Air/Water Ambulance Services Medical GuidelineWPS Health Insurance2026-10-01
    Non-Emergent Ambulance ServicesConnectiCare2026-09-11
    Fixed Wing Air Ambulance TransportCigna2026-08-15
    Air AmbulanceAmbetter Georgia2026-08-01
    Ambulance Services (for New Mexico Only)UnitedHealthcare2026-08-01
    Ambulance Services (for Tennessee Only)UnitedHealthcare2026-08-01
    Clinical Policy: Air AmbulanceAmbetter Nevada2026-08-01
    Air AmbulanceCentene2026-08-01
    Clinical Policy: Air AmbulanceArizona Complete Health2026-08-01

    Related Codes

    HCPCS-LEVEL-II-S2152-SOLID-ORGAN-TRANSPLANTATION-GLOBAL-CARE

    HCPCS Level II S2152: Solid Organ Procurement and Transplantation

    HCPCS-LEVEL-II-S2266-INDUCED-ABORTION-29-TO-31-WEEKS

    HCPCS Level II S2266: Induced Abortion, 29 to 31 Weeks

    HCPCS-LEVEL-II-S3630-EOSINOPHIL-COUNT-BLOOD-DIRECT

    HCPCS Level II S3630: Eosinophil Count, Blood, Direct

    HCPCS-LEVEL-II-S4017-INCOMPLETE-ART-CYCLE-CANCELLED-PRIOR-TO-STIMULATION

    HCPCS Level II S4017: Incomplete Cycle — Cancelled Prior to Stimulation

    HCPCS-LEVEL-II-S8055-ULTRASOUND-GUIDANCE-MULTIFETAL-REDUCTION-TC

    HCPCS Level II S8055: Ultrasound Guidance for Multifetal Pregnancy Reduction

    HCPCS-LEVEL-II-S8940-EQUESTRIAN-HIPPOTHERAPY-PER-SESSION

    HCPCS Level II S8940: Equestrian/Hippotherapy, Per Session

    HCPCS-LEVEL-II-S9024-PARANASAL-SINUS-ULTRASOUND

    HCPCS Level II S9024: Paranasal Sinus Ultrasound

    HCPCS-LEVEL-II-S9366-HOME-TPN-1-2L-PER-DAY-HOME-INFUSION

    HCPCS Level II S9366: Home Infusion TPN, 1–2 L/day

    HCPCS-LEVEL-II-S9446-GROUP-PATIENT-EDUCATION-NON-PHYSICIAN

    HCPCS S9446: Patient Education, Non-Physician Provider, Group, Per Session

    HCPCS-LEVEL-II-S9451-EXERCISE-CLASS-NON-PHYSICIAN-SESSION

    HCPCS S9451: Exercise Classes, Non-Physician Provider, Per Session

    Showing 1–10 of 532

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    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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    Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

    Represents other home-based services that may coordinate with S9559 in a comprehensive home infusion or home health program