Medical supplies are reported using HCPCS Level II codes, a standardized coding system maintained by the U.S. Centers for Medicare & Medicaid Services (CMS). These alphanumeric codes cover products and supplies that fall outside the scope of CPT codes, which focus on physician services and procedures. If you’re billing for durable medical equipment, prosthetics, orthotics, or disposable supplies, HCPCS Level II is the code set you need.
How HCPCS Level II Differs From CPT
The Healthcare Common Procedure Coding System (HCPCS) has two subsystems. Level I is the CPT code set, maintained by the American Medical Association. CPT codes are five-digit numeric codes that identify medical services and procedures: office visits, surgeries, lab tests, imaging, and anesthesia. They cover what a clinician does, not the physical products used.
Level II fills the gap. It was created specifically to identify products, supplies, and services that CPT doesn’t cover. That includes ambulance services, certain drugs and biologicals, and the broad category known as DMEPOS: durable medical equipment, prosthetics, orthotics, and supplies. Wheelchairs, oxygen equipment, surgical dressings, diabetic testing supplies, and infusion pumps all fall under Level II.
The structural difference is easy to spot. CPT codes are five numeric digits (like 99213). HCPCS Level II codes start with a single letter followed by four numbers (like E0601 for a continuous positive airway pressure device). If a code begins with a letter, you’re working in Level II territory.
What HCPCS Level II Codes Cover
The code set is organized into alphabetic ranges, each covering a different category of products and services. Durable medical equipment, one of the largest sections, spans codes E0100 through E8002. Within that range you’ll find subcategories for hospital beds, traction devices, respiratory equipment, wheelchairs, and more.
Other letter ranges cover additional supply types. A codes handle transportation and certain medical and surgical supplies. B codes cover enteral and parenteral nutrition. K codes are temporary codes often assigned to durable medical equipment that doesn’t yet have a permanent code. L codes cover orthotics and prosthetics. The system also includes miscellaneous or “not otherwise classified” codes scattered throughout, which providers use when no existing code accurately describes the item being billed.
When To Use Level II vs. Level I
The general rule is straightforward: use CPT (Level I) to report what the provider did, and use HCPCS Level II to report what product or supply was provided. A physician performing a knee replacement bills the surgical procedure with a CPT code, but the prosthetic knee component itself gets a separate HCPCS Level II code.
This distinction matters most for items used outside a physician’s office. If a patient receives durable medical equipment at home, such as an oxygen concentrator or a hospital bed, those items are reported exclusively with Level II codes. Supplies dispensed during an in-office procedure may already be bundled into the CPT code for that procedure, so you wouldn’t always bill them separately. The key question is whether the supply is included in the service code or needs to stand on its own.
Modifiers That Affect Supply Billing
HCPCS Level II codes often require two-character modifiers that tell the payer important details about how the supply is being provided. The most common is the RR modifier, which indicates the item is being rented rather than purchased. For equipment like oxygen systems or infusion pumps, you’ll typically bill with RR and a date span covering the rental period, where one unit equals one month of rental.
Another modifier, KR, signals a short-term or one-day test use, such as an overnight trial of a breathing device. The correct modifier changes how the payer processes the claim and what reimbursement applies, so selecting the wrong one can delay or deny payment.
Who Maintains the Code Set
CMS is responsible for all additions, revisions, and deletions to HCPCS Level II. The code set is updated quarterly, with new files typically released in January, April, July, and October. This is faster than the annual CPT update cycle and reflects the pace at which new medical products enter the market. CMS publishes each quarterly update as a downloadable public use file on its website, so coders and billing departments can stay current without waiting for a printed annual edition.
Documentation Needed To Support These Codes
Selecting the right HCPCS Level II code is only part of the process. Every claim for medical supplies billed to Medicare requires a written order or prescription from the treating practitioner, known as a standard written order. Beyond that, suppliers must have medical record documentation supporting the medical necessity of the item, proof that it was actually delivered to the patient, and correct coding on the claim itself. Missing any of these elements, particularly the written order or proof of delivery, is one of the most common reasons supply claims get denied.
For items that patients use on an ongoing basis, such as continuous glucose monitors or home oxygen, documentation must also show continued need and use. A one-time prescription isn’t always enough to support months of recurring supply claims.