@Sbr, as far as I know, national Medicare has made O2 coverage optional for the regional Medicare offices. I don't know of a more recent policy statement (but maybe there is one). It has been my understanding that practically all of those regional offices are authorizing coverage. The legal language says, "[C]overage determinations will be made by the Medicare Administrative Contractors under section 1862(a)(1)(A) of the Social Security Act, as allowed and described in Chapter 1, Section 240.2 (Home Use of Oxygen), Subsection D, of Publication 100-03 of the NCD Manual." The Medicare Administrative Contractors [MACs] are listed here -- https://www.cms.gov/medicare/coding-billing/medicare-administrative-contractors-macs/who-are-macs -- and I suppose it might be feasible to call yours and ask.