## **What is a miscellaneous DME supply?**
HCPCS code A9900 refers to “Miscellaneous DME supply, accessory, and/or service component of another HCPCS code.” This code is used when a DME item or accessory—such as tubing, connectors, or specialized fittings—does not have its own distinct HCPCS code but is required as part of another piece of durable medical equipment (e.g., oxygen systems, CPAP units, or mobility aids).
Because A9900 is a miscellaneous code, it is considered a catch-all for unclassified DME-related supplies or services that are necessary for equipment operation, fitting, or maintenance but are not separately identified elsewhere.
Medicare and other payers typically require detailed documentation to determine medical necessity and prevent duplicate billing, as many items that might seem eligible under A9900 may already be included in another supply or equipment code.
## **HCPCS code A9900 documentation requirements**
When billing for A9900, documentation must clearly support the medical necessity and explain why a more specific HCPCS code does not exist for the supplied item or service. Complete and detailed information helps assist providers and payers in verifying that the claim meets coverage and access requirements. The following documentation elements are typically required:
- Detailed description of the item or service provided (e.g., "custom oxygen tubing connector").
- Link to the primary DME item the supply or service supports, including its HCPCS code.
- Justification of need, including how the item or service enables the patient to effectively use or maintain the primary DME.
- Physician’s order or supplier’s record, showing the item’s purpose, quantity, and date of service.
- Complete information must be included in the claim note field to help MACs understand the nature of the supply or service and its relationship to the primary equipment.
Including a clear note and complete supporting documentation helps ensure that reviewers can easily verify the purpose and necessity of the billed item. Claims lacking adequate item descriptions or justification are commonly denied by Medicare Administrative Contractors (MACs) for insufficient documentation or lack of medical necessity.
## **Billing requirements for A9900**
Items billed with A9900 are frequently denied by Medicare as included in the primary DME payment (CARC 97). However, some commercial or Medicaid payers may allow limited reimbursement. Billing guidance for this code is as follows:
- The item is not bundled with the primary DME reimbursement.
- The payer’s policy explicitly allows miscellaneous supplies to be billed using A9900 with supporting documentation.
- If a supplier chooses to bill separately for a component that is included in another HCPCS code, A9900 must be used to represent that component.
- Report A9900 only when no other code appropriately describes the supply or accessory.
- Always include a detailed narrative description on the claim to explain the item or service.
- For Medicare claims, expect that payment will be denied as non-covered unless prior authorization or an Advance Beneficiary Notice (ABN) is issued for patient responsibility.
- For commercial payers, coverage varies; always verify payer-specific guidelines before submission.
## **Applicable modifiers**
Modifiers clarify the relationship of the A9900 supply or service to the primary equipment and the circumstances of use. Commonly applicable modifiers include:
- **RR** – Rental (used when the supply or service is associated with rented DME).
- **UE** – Used equipment (if the accessory or part is for previously owned equipment).
- **GA** – When an ABN is issued, it indicates the patient may be responsible for non-covered charges.
Append modifiers to the A9900 line only if the payer requires them for that item.
## **Other relevant codes**
- **A9999**: Miscellaneous DME supply or accessory, not otherwise specified
- **E1399:** Durable medical equipment, miscellaneous
Frequently asked questions
