Medicare Part B covers home oxygen equipment and supplies, but only when specific medical criteria are met and the right paperwork is in place. The process starts with a qualifying test at your doctor’s office, followed by a formal certification, and then an order through a Medicare-enrolled supplier. Here’s what each step involves and what you’ll pay out of pocket.
The Blood Oxygen Levels Medicare Requires
Medicare doesn’t cover oxygen simply because your doctor recommends it. You need a documented test showing your blood oxygen has dropped below a specific threshold. There are two ways to measure this: an arterial blood gas test (a blood draw from an artery) or a pulse oximetry reading (the clip placed on your finger). The numbers Medicare looks at fall into two groups.
Group I is the most straightforward path to coverage. You qualify if your oxygen level at rest, while breathing normal room air, is at or below 88% saturation (or a partial pressure of oxygen at or below 55 mm Hg on a blood gas test). If your resting levels are above that cutoff but drop to 88% or below during sleep or exercise, you can still qualify, though Medicare will only cover oxygen use during the specific activity where the drop was documented.
Group II covers a narrower situation. If your oxygen saturation is 89% or your partial pressure falls between 56 and 59 mm Hg, Medicare will pay for oxygen only if you also have one of three complications: swelling in the legs or ankles from heart failure, elevated pressure in the blood vessels of the lungs, or a red blood cell count that’s abnormally high (hematocrit above 56%). Without one of those additional findings, levels in this borderline range won’t qualify.
What Your Doctor Needs to Do
Your physician must complete a Certificate of Medical Necessity, known as CMS Form 484. This is a standardized federal form that documents your diagnosis, your qualifying test results, and the prescribed flow rate of oxygen. Without it, Medicare will deny the claim regardless of how low your oxygen levels are.
A few practical details matter here. The qualifying test needs to be performed under the right conditions: at rest while breathing room air for a standard claim, or during exercise or sleep if you’re seeking coverage specifically for those situations. Make sure your doctor’s office knows the test needs to meet Medicare’s documentation standards before it’s done, not after. If the test is performed while you’re already on supplemental oxygen, or if the results aren’t clearly recorded, the form may be rejected. Ask your doctor’s office directly whether they’ve completed CMS Form 484 and whether it’s been sent to the supplier.
Choosing a Medicare-Enrolled Supplier
You can’t buy or rent oxygen equipment from just any company and expect Medicare to reimburse you. The supplier must be enrolled in the Medicare program. Your doctor’s office can typically refer you to one, or you can search for suppliers in your area through Medicare.gov.
The supplier handles the equipment delivery, setup, and ongoing service. Once the order is placed and the Certificate of Medical Necessity is on file, the supplier bills Medicare directly. They’re also required to provide you with the amount of oxygen your doctor prescribed each month, along with all necessary accessories.
How the 36-Month Rental Works
Medicare treats home oxygen as a rental, not a purchase. You’ll receive monthly rental payments for up to 36 months. These payments cover the oxygen equipment itself plus all related accessories and services: tubing, cannulas, masks, mouthpieces, humidifiers, regulators, delivery of oxygen contents, backup equipment, maintenance, and repairs. You shouldn’t be billed separately for any of those items during the rental period.
The supplier who provides equipment in the first month is locked in for the entire 36-month period. They can’t hand you off to a different company, and they’re responsible for keeping everything in working order. If your concentrator breaks in month 14, they fix or replace it at no extra charge to you.
After the 36 months of rental payments end, Medicare stops paying for the equipment, but the supplier is still required to provide it, along with accessories, maintenance, and repairs, for the remainder of a five-year period called the “reasonable useful lifetime.” For concentrators, Medicare will pay for a maintenance and servicing visit no more often than every six months, starting six months after the rental period ends. Gaseous and liquid oxygen systems don’t get separate maintenance payments.
What Happens After Five Years
The five-year clock starts on the date you first received the equipment, not on the date you stopped paying rental fees. Once those five years are up, you can choose to get entirely new equipment. If you do, a new 36-month rental period and a new five-year useful lifetime both start fresh. If you have both stationary and portable equipment, both must be replaced at the same time when the stationary equipment’s five-year period ends.
One important detail: if you choose not to replace your equipment after the five-year period and the supplier transfers ownership to you, Medicare will no longer cover maintenance and servicing for that equipment. At that point, you’d be responsible for any repair costs yourself.
Your Out-of-Pocket Costs
Home oxygen is classified as durable medical equipment under Medicare Part B. That means you’ll pay 20% of the Medicare-approved amount for each monthly rental, and Medicare covers the remaining 80%. You’ll also need to meet your annual Part B deductible first, which is $283 in 2026. Once that deductible is met, the 20% coinsurance applies for the rest of the year.
If you have a Medicare Supplement (Medigap) plan, it may cover some or all of that 20% coinsurance depending on your plan type. Medicare Advantage plans also cover oxygen but may have different cost-sharing rules, so check with your specific plan.
What’s Included in Coverage
The monthly rental payment is meant to be comprehensive. It covers:
- Stationary equipment like an oxygen concentrator for home use
- Portable equipment such as portable concentrators or small oxygen tanks for leaving the house
- All accessories including tubing, cannulas, masks, face tents, oxygen conserving devices, humidifiers, nebulizers for humidification, regulators, and equipment stands
- Oxygen contents if you use a system that requires refills (liquid or gaseous tanks)
- Delivery, maintenance, and repairs for the duration of the rental and through the five-year useful lifetime
Your supplier is required to provide any accessory your treating doctor orders. If a supplier tells you a particular item isn’t covered or tries to charge you separately for tubing or a cannula during the rental period, push back. Those costs are bundled into the monthly payment Medicare is already making.
Common Reasons Claims Get Denied
Most denials come down to documentation problems rather than medical need. The qualifying test may have been done under the wrong conditions, the Certificate of Medical Necessity may be incomplete or missing, or the oxygen saturation reading may have been a single digit above the cutoff. If your resting oxygen is 89% or 90%, you won’t qualify under Group I criteria, even if you feel short of breath.
If your levels are borderline, ask your doctor about testing during exercise or sleep. Many people whose resting levels are acceptable see significant drops during a six-minute walk test, which can open the door to coverage for oxygen during physical activity. Similarly, overnight pulse oximetry can document drops during sleep that don’t show up during a daytime office visit.
If your claim is denied, you have the right to appeal. The first step is a redetermination request, which must be filed within 120 days of the denial notice. Your doctor can submit additional documentation or clarify the original test results during the appeal. Many initial denials are overturned when the paperwork issues are corrected.