Glossary / CMN and DIF
CMN and DIF Certificate of Medical Necessity and DME Information FormCMN and DIF (Certificate of Medical Necessity and DME Information Form)
The CMS forms (the CMS-484 oxygen CMN and others) that certain DME claims once required; retired for dates of service on or after January 1, 2023.
A Certificate of Medical Necessity (CMN) was a CMS form the treating physician completed to attest that an item was medically necessary; a DME Information Form (DIF) was the supplier-completed equivalent for certain items. For years, claims for oxygen, pneumatic compression devices, osteogenesis stimulators, TENS units, seat lift mechanisms, external infusion pumps, and enteral and parenteral nutrition could not be paid without one.
CMS eliminated all CMNs and DIFs for claims with dates of service on or after January 1, 2023, after concluding the forms duplicated information already on the claim or in the medical record. The retired forms are CMS-484, CMS-846, CMS-847, CMS-848, CMS-849, and CMS-854 (CMNs) and CMS-10125 and CMS-10126 (DIFs). Claims for later dates of service that still carry CMN or DIF data are rejected and returned.
The medical necessity requirement did not go away; it moved. Everything a CMN used to certify now has to be found in the contemporaneous medical record and the Standard Written Order. That is why an oxygen claim now hinges on the actual blood-gas report in the chart rather than a physician's signature on a form.
Common questions
Do I still need a CMN for oxygen?
No, not for dates of service on or after January 1, 2023. The qualifying test results and clinical findings must instead be in the practitioner's record.
Should I keep old CMNs?
Yes, for claims with dates of service before 2023, which can still be reviewed or appealed. Keep them with the rest of the claim file.
What replaced the CMN in a case file?
The SWO plus the clinical notes; AffirmDME reads the necessity criteria out of the chart notes, which is where reviewers now look.
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Sources: CMS news alert: Discontinuing the use of CMNs and DIFs · CMS MLN SE22002: Elimination of Certificates of Medical Necessity and DME Information Forms · DME MAC Article A55426 — Standard Documentation Requirements . Definitions summarize public Medicare policy and are not legal or billing advice.
More terms
- ADR — Additional Documentation Request
- Prior authorization
- Affirmation and non-affirmation
- UTN — Unique Tracking Number
- SWO — Standard Written Order
- Face-to-face encounter
- DME MAC — Durable Medical Equipment Medicare Administrative Contractor
- Jurisdiction
- PTAN — Provider Transaction Access Number
- NPI — National Provider Identifier
- MBI — Medicare Beneficiary Identifier
- LCD — Local Coverage Determination
- NCD — National Coverage Determination
- Policy article
- HCPCS — Healthcare Common Procedure Coding System
- Length of need
- Prior authorization exemption
- Competitive bidding
- Proof of delivery
- TPE — Targeted Probe and Educate
- Prepayment review