A "Certificate of Medical Necessity" (CMN) is a document that many insurance companies, including Medicare and Medicaid, require when a physician is prescribing a costly item of medical equipment.

Most health insurance programs will cover some or all of the cost of necessary durable medical equipment. Because this equipment is expensive, and it is often needed for months, if not years, insurance companies want to be sure that this medical equipment is really necessary. It's not unheard of for patients or their families to want certain equipment more for convenience than because they truly need it to treat or manage a medical need. Insurance companies hate that.

Fully automatic hospital beds, special mattresses for the treatment of pressure sores, oxygen, certain wheelchairs, and seat lift mechanisms are some of the more familiar items that will require a CMN before Medicare, Medicaid and many other insurance companies will approve payment.

The Certificate of Medical Necessity is usually prepared by the durable medical equipment provider who will be delivering the item to the patient. The document is forwarded to the physician for signature, and the equipment company coordinates submitting the necessary information to Medicare (for sake of this discussion we'll use "Medicare" as our example insurance company).

There must be clinical information in the doctor's chart to support the need for each particular piece of equipment ordered. The doctor may not be required to submit this additional information, but it must be there just in case.

Without a Certificate of Medical Necessity, Medicare will not cover the cost of equipment requiring a CMN. It is, therefore, very important to verify that the medical equipment company has the required authorization before you take delivery. If Medicare has not authorized coverage you could end up with a very expensive bill for equipment rental.

The CMN is not something that a caregiver or patient should have to "mess" with. There are times, though, when CMN paperwork can disappear on a doctor's desk. If your medical equipment supplier says they have submitted the documents to the doctor and are having trouble getting it signed, you may have to get involved. The most productive thing you can do is ask your supplier for a copy of the Certificate and hand carry it to the doctor. Either say you will wait until the doctor has signed the CMN or, if that will be a futile endeavor, say you will return the next day to pick it up in person. If the doctor is in the office, his staff may help move things along just to get you out of their waiting room.

Don't attempt to find the appropriate CMN document for your specific need on the Internet. While you may find something that looks correct, you won't be able to tell whether it's the one currently in use. They are revised from time to time. Your durable medical equipment provider will always have the most recent, correct version and will know how to complete it correctly. You should never attempt to fill out these documents yourself. Errors will simply result in rejection. Leave it to your DME company. They know how to complete these documents correctly.