## **What is a miscellaneous DME supply or accessory?**
HCPCS code A9999 represents miscellaneous durable medical equipment (DME) supplies or accessories not otherwise classified by a specific HCPCS code. Use A9999 only when no existing HCPCS code accurately describes the item.
These items may include unique wheelchair parts, pump tubing, custom kits, or other DME supply or accessory components that are necessary for a patient's treatment but not clearly listed under standard codes. For billing A9999, providers must submit a detailed description, including manufacturer, model number, product function, and a comprehensive clinical justification demonstrating medical necessity
Medicare administrative contractors (MACs) and commercial payers typically require extensive documentation for A9999 because it is a non-specific, miscellaneous code lacking a defined national payment amount
Coverage decisions and reimbursement vary, and payment is only issued if the claim demonstrates that the supply is essential for the proper use of a covered DME item. In other words, A9999 serves as a "catch-all" billing option for medically necessary but not otherwise specified accessories or supplies.
## **HCPCS code A9999 documentation requirements**
Providers should include:
- Detailed description of the supply or accessory – include manufacturer, model, and function.
- Clinical rationale tied to patient needs or condition – show how the supply supports the patient’s treatment or the effective use of durable medical equipment.
- Evidence of non-duplication – explain why no other, more descriptive HCPCS code applies.
- Invoice or catalog information – many payers require cost documentation to establish pricing.
**Special use case: CGM adjunctive supplies**
For adjunctive continuous glucose monitor (CGM) supplies used with external insulin infusion pumps, CMS mandates inclusion of the word “adjunctive” on claims. This is typically submitted in the NTE segment (loops 2300/2400) on electronic claims, or in Item 19 on paper CMS-1500 forms.
## **A9999 billing guidelines**
When billing A9999, providers must document medical necessity and confirm that no existing specific HCPCS code applies to the supply or accessory. Claims must include a clear description of the supply or accessory and why an alternate code (e.g., A4238, A4239) is not appropriate.
For adjunctive CGM supplies used with insulin pumps, A9999 is the appropriate code and may represent all components (sensor, transmitter, insertion tools). Claims must include the word “adjunctive” to ensure correct processing.
Medicare MACs or commercial payers locally determine reimbursement, as A9999 does not have a fixed national fee schedule. Always verify payer-specific rules before billing.
Note that A9999 frequently triggers medical review or manual claim adjudication due to its nonspecific nature. This code generally cannot be billed for entire DME devices but only for supplies and accessories.
## **Other relevant codes**
Other HCPCS codes related to miscellaneous DME supplies or accessories include:
- **A9900** – Miscellaneous DME supply, accessory, or service component related to another HCPCS code; used when an item is separately billable but no specific HCPCS code exists.
- **A9901** – DME delivery, setup, and/or dispensing service component of another HCPCS code. Used when documenting the service component linked to DME delivery or fitting.
- **E1399** – Durable medical equipment, miscellaneous. This code applies to device-related items and may be used instead of A9999, depending on context and correct coding requirements.
The following codes help clarify proper reporting for unclassified or not otherwise specified (NOS) DME items, ensuring compliance with payer rules and accurate claim adjudication.
Frequently asked questions
