Tip for CMS-484 / CMS-846 / CMS-849 / CMS-854

CMNs are required for specific DME categories: oxygen, hospital beds, wheelchairs, support surfaces, and others

Tip for CMS-484 / CMS-846 / CMS-849 / CMS-854

The physician must sign the CMN — the DME supplier can complete sections but cannot sign for the physician

Tip for CMS-484 / CMS-846 / CMS-849 / CMS-854

Ensure all clinical questions on the CMN are answered completely — blank fields cause claim rejections

Durable Medical EquipmentmoderateDoctor signature required

Certificate of Medical Necessity (CMN)

CMS-484 / CMS-846 / CMS-849 / CMS-854 · CMS

Certificate of Medical Necessity for Medicare-covered DME. Different form numbers for different equipment categories: CMS-484 (oxygen), CMS-846 (pneumatic compression), CMS-849 (seat lift), CMS-854 (power mobility).

Form Details

Total fields: 35
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Where to Submit This Form

📠

Fax to the DME Medicare Administrative Contractor (MAC)

The DME supplier prepares the CMN and obtains the physician's signature before submitting to the DME MAC.

📬

Mail to the DME MAC with the claim

Filing Deadline

Must be completed and signed before or at the time the DME is provided. The physician must sign the CMN — stamped or electronic signatures may not be accepted for all items.

Required Attachments

📎 Completed Certificate of Medical Necessity (CMS form specific to the DME category)
📎 Physician signature and date
📎 Detailed written order for the DME item
📎 Medical records supporting the clinical need
📎 Face-to-face encounter documentation (required for some items)

Processing Time

Part of the Medicare claim process. Claims with valid CMNs are typically processed within 30 days. Incomplete or incorrect CMNs will be returned, delaying payment.

What Happens Next

The DME MAC reviews the CMN with the claim. If the CMN supports medical necessity, the claim is paid. CMNs are required for recertification at specified intervals depending on the equipment type.

Tips for This Form

✓ CMNs are required for specific DME categories: oxygen, hospital beds, wheelchairs, support surfaces, and others
✓ The physician must sign the CMN — the DME supplier can complete sections but cannot sign for the physician
✓ Ensure all clinical questions on the CMN are answered completely — blank fields cause claim rejections
✓ CMN recertification intervals vary by equipment type — oxygen CMNs are revised at 12 months, while others may differ

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