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Home infusion coding Resource Center

Working to Achieve Nationally Standardized, Sensible Electronic Claiming and Coding for Home Infusion

Standardized electronic claiming and coding for home infusion is one of NHIA’s top priorities and our hard work on this important issue brought about a significant victory in 2001 when the federal government’s HCPCS administrators published national standardized coding for home infusion therapy services effective in January of 2002. Since then, the HCPCS per diem S-code system has been widely adopted by commercial payers and some government payers throughout the nation. These codes are compliant with federal Health Insurance Portability and Accountability Act (HIPAA) regulations that mandate that all public and private payers use “approved” standardized coding for all of their health care transactions.

To help payers and providers of home infusion services comply with these requirements, in January 2002 NHIA released its first version of the educational resource, the NHIA National Coding Standard for Home Infusion Claims Under HIPAA. 

The 2024 NHIA National Coding Standard has been updated to include new home infusion service codes and changes to the description of existing codes. These changes were a result of NHIAs ongoing efforts to modernize the home infusion code set to reduce the need to utilize not otherwise classified (NOC) codes by expanding the code set to account for newer drug therapies that have come to market since the S-code set was first introduced 20+ years ago. Significant changes from the previous version are highlighted in red within the document.   

NHIA also offers three downloadable coding references to our members.

What is a Per Diem? The NHIA National Definition of Per Diem

The standardization of pertinent and relevant definitions is inherently advantageous to all stakeholders within the health care delivery system. Such standardization reduces the chance of differing expectations amongst stakeholders, encourages benchmarking and analysis that is based upon comparable data sets, and generally fosters communication and cooperation between the various entities responsible for providing medically necessary health care services. With infusion therapy, reimbursement is often based upon a per diem approach, yet frequently this term is left undefined. Accordingly, as the national organization representing infusion services, the National Home Infusion Association (NHIA) presents the following definition of the term “per diem.”

As related to reimbursement, the term “per diem” represents each day that a given patient is provided access to a prescribed therapy, beginning with the day the therapy is initiated and ending with the day the therapy is permanently discontinued. The term “permanently” shall not be construed to infer that a therapy shall never again be initiated, but rather that continuation of the therapy is simply not predicted or anticipated at the time of cessation. The expected course and duration of the treatment shall be determined by the plan of care as prescribed by the ordering physician.

It shall not be necessary for the patient to receive an actual drug infusion each and every day in order to be considered covered under an existing per diem, so long as additional infusions are anticipated in the near future as prescribed in the physician plan of care. The fact that the health care provider anticipates continued responsibility for the patient and incurs costs related to such responsibilities, remains accountable for the provision of such anticipated care, and is responsible for the acquisition and allocation of resources that will be necessary to meet these obligations, shall deem the existing per diem to be current, valid, and in force.

This definition is valid for per diem therapies of duration of up to and including every 72 hours. Therapies provided beyond this range (weekly, monthly, etc.) fall outside of the per diem structure, and should have separate reimbursement rates that are specified on a contractual or other basis.


Examples: For purpose of demonstration, the following examples are provided:

Prescribed TherapyUnits of Service
Infusion every 4 hours for 14 days14
Infusion every 8 hours for 14 days14
Infusion every 12 hours for 14 days14
Infusion every 24 hours for 14 days14
Infusion every 48 hours for 14 days14
Infusion every 72 hours for 14 days14
Infusion once per week1 (per week)
Infusion once per month1 (per month)

Costs associated with therapies that are of a more infrequent nature (72 hours, 48 hours, etc.) are less than those that are more frequent, and decreased reimbursement for such services is thereby appropriate. Using the above as an example, it is expected that the “Every 72 hours” per diem would be reimbursed at lesser daily rate than the “Every 4 hours” per diem, and that the units of service would remain identical.

Per diem reimbursement is intended to compensate for costs plus a fair return, i.e. the excess of revenues over expenses needed to ensure continued access to these therapies, for the following services, products and other support costs of an infusion therapy provider:


Professional Pharmacy Services


Medication profile set-up and drug utilization review

Monitoring for potential drug interactions

Sterile procedures including intravenous admixtures, clean room upkeep, vertical and horizontal laminar flow hood certification, and all other biomedical procedures necessary for a safe environment

USP-797 compliant sterile compounding of medications

Patient counseling as required under OBRA 1990

Clinical Monitoring

Development and implementation of pharmaceutical care plans

Pharmacokinetic dosing

Review and interpretation of patient test results

Recommending dosage or medication changes based on clinical findings

Initial and ongoing pharmacy patient assessment and clinical monitoring

Measurement of field nursing competency with subsequent education and training

Other professional and cognitive services as needed to clinically manage the patient pharmacy care


Care Coordination

Patient admittance services, including communication with other medical professionals, patient assessment, and opening of the medical record

Patient/caregiver educational activities, including providing training and patient education materials

Clinical coordination of infusion services care with physicians, nurses, patients, patient’s family, other providers, caregivers and case managers

Clinical coordination of non-infusion related services

Patient discharge services, including communication with other medical professionals and closing of the medical record

24 hours/day, 7 days/week availability for questions and/or problems of a dedicated infusion team consisting of pharmacist(s), nurse(s) and all other medical professionals responsible for clinical response, problem solving, trouble shooting, question answering, and other professional duties from pharmacy staff that do not require a patient visit

Development and monitoring of nursing care plans

Coordination, education, training and management of field nursing staff (or sub-contracted agencies)

Delivery of medication, supplies and equipment to patient’s home


Supplies and Equipment

DME (pumps, poles and accessories) for drug and nutrition administration

Equipment maintenance and repair (excluding patient owned equipment)

Short peripheral vascular access devices

Needles, gauze, non-implanted sterile tubing, catheters, dressing kits and other necessary supplies for the sale and effective administration of infusion, specialty drug and nutrition therapies


Multiple Categories of Pharmacy Professional Services

Maintaining comprehensive knowledge of vascular access systems

Continuing education to professional pharmacy staff

Removal, storage and disposal of infectious waste

Maintaining accreditation, including:

  • Outcomes assessments and analysis
  • Ongoing staff development and competency assessment
  • Continuous quality assessment and performance improvement programs
  • All other policies and procedures necessary to remain in compliance with The Joint Commission, Community Health Accreditation Program (CHAP), Accreditation Commission for HealthCare (ACHC), and other professional accreditation standards
  • Certification fees and expenses
  • Other applicable accreditation expenses

Maintaining the substantial insurance requirements (e.g. liability), including compliance with all state and federal regulations related to minimal insurance coverage


Administrative Services

Administering coordination of benefits with other insurers

Determining insurance coverage, including coverage for compliance with all state and federal regulations

Verification of insurance eligibility and extent of coverage

Obtaining certificate of medical necessity and other medical necessity documentation

Obtaining prior authorizations

Performing billing functions

Performing account collection activities

Internal and external auditing and other regulatory compliance activities

Retrieval and storage of medical and reimbursement records

Maintaining inventories of drugs, equipment, administration supplies and office supplies

Maintaining physical plant and offices, including building, equipment and furnishings, utilities, telephone, pagers, office supplies, etc.

Maintaining computer clinical and administrative information systems

Postage and shipping

Design and production of patient education materials

Quality assessment and improvement activities

Continuing education to administrative staff

Legal and accounting services

Licensing application activities and fees


Other Support Costs

Wages, salaries, benefits, payroll taxes, FICA, unemployment insurance, and workers compensation premiums

Property taxes

Asset depreciation

Inventory carrying costs

Accounts receivable carrying costs associated with carrying of large accounts receivable balances

Costs of insurance coverage per state regulations

Costs of maintaining accreditation (The Joint Commission, CHAP, ACHC, etc.)

New product research and development

Sales, advertising, and marketing

Community commitment and charitable donations

Cost of bad debt (uncollectible accounts receivable)

Other applicable overhead and operational expenses


Products and Services Not Included in the Definition of Per Diem

All drugs*, biologicals, enteral formulae and blood products

Nursing services provided directly to patients in their residences or other alternate sites

Other services provided directly to patients in their residences or other alternate sites by provider’s staff or representatives (e.g. dietician for nutritional counseling)

PICC and Midline insertion procedures and associated supplies

Surgically implanted central vascular access devices

Invasively placed digestive tract access devices for enteral therapy, including G tubes, NG tubes, J tubes, etc.

Services and products not considered part of the per diem compensation as may be agreed to by provider and payer (e.g. delivery to high risk areas with escort or extra protection, wound care supplies and devices for sites other than IV catheter insertion sites, etc.)

Services and products that may be provided at request of the patient that are considered by provider to be not medically necessary and beyond the scope of inclusion in the per diem

All services and products provided when not otherwise paid for through per diem coding for a therapy episode.


Summary. As the national standardization of relevant and pertinent definitions is deemed inherently advantageous to all stakeholders; and as NHIA is the national organization representing infusion services and standards, it is hereby established that the preceding definition of the phrase “per diem” is the national standard for purposes associated with infusion therapy reimbursement.