Medication Assisted Treatment and Methadone Treatment do not have to be the same thing. Suboxone is actually considered a better drug than methadone for addiction. Both Methadone and Buprenorphine (a component of suboxone) can be prescribed to anyone by any physician for
pain; to be prescribed for addiction, methadone MUST be prescribed in a Methadone Clinic; Buprenorphine must be prescribed by a provider that has what is called an "X license" or Data Waiver (their DEA number starts with an X instead of another letter).
How did they get licensed as a methadone provider without knowing how to bill it, or whether it will be financially feasible to start a methadone clinic?? -- Rhetorical question, people do things like this all the time and it blows my mind.
Here is the Medicare information sheet, including codes:
https://www.cms.gov/files/document/otp-billing-and-payment-fact-sheet-printer-friendly.pdf
The Medicaid HMO/other programs will have their own billing guides. I would suggest contacting them.