HCPCS Code E1390: Oxygen concentrator, single delivery port billing guide

Key Takeaways

HCPCS code E1390 describes a stationary oxygen concentrator with a single delivery port, capable of delivering 85% or greater oxygen concentration at the prescribed flow rate

E1390 is a HCPCS Level II code maintained by CMS, not a CPT code. Its true single-vs-dual counterpart is E1391 (dual delivery port); E1392 is a separate, portable rental code

CMS retired the paper Certificate of Medical Necessity, including Form 484 for oxygen, for claims with dates of service on or after January 1, 2023; a standard written order plus supporting medical-record documentation now establishes medical necessity

New oxygen rental periods starting on or after April 1, 2023 require modifier N1, N2, or N3, matched to the beneficiary’s LCD coverage group, in place of KX

Practice management software like Pabau can help a practice keep orders, test results, and clinical notes organized in one place, so records are ready if a payer asks for them

A denied E1390 claim rarely comes down to the wrong code. It usually comes down to the paperwork behind it, an outdated form or the wrong modifier. Sometimes it’s a qualifying test that never made it into the file.

HCPCS code E1390 covers an oxygen concentrator with a single delivery port. It delivers 85 percent or greater oxygen concentration at the prescribed flow rate. Medicare pays for it as a monthly DME rental, but only when the documentation backs it up.

Two things changed the E1390 playbook in the last few years. CMS retired the paper medical necessity certificate, and new oxygen rentals now carry a different modifier. Get both right, and the code itself is the easy part.

What HCPCS code E1390 covers

Most code-selection mistakes with E1390 come from confusing HCPCS Level II with CPT. The other common mistake is mixing it up with a close relative. Neither error is hard to avoid once you know exactly what the code says.

The official CMS descriptor for E1390 is short but specific: oxygen concentrator, single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate. It bills a stationary concentrator with one outlet, for a single beneficiary in one location.

A note on the “E1390 CPT code” search: E1390 isn’t a CPT code. CPT codes are maintained by the American Medical Association and describe physician services. HCPCS Level II codes like E1390 are maintained by CMS and cover equipment, supplies, and non-physician services, including DME. Both sets support Medicare billing, but they run on separate update cycles.

Medicare coverage: When E1390 counts as medically necessary

Medicare Part B covers E1390 under the DME benefit, but coverage isn’t automatic. A beneficiary has to meet the Oxygen and Oxygen Equipment LCD’s clinical criteria. The supplier also needs the supporting documentation on file before delivery.

The LCD generally requires one of the following, confirmed by arterial blood gas or oximetry testing. Check the current LCD with your MAC, since thresholds can be revised:

• SpO2 (oxygen saturation) at or below 88%, or
• PaO2 (arterial oxygen tension) at or below 55 mmHg, or
• PaO2 between 56 and 59 mmHg with a qualifying comorbidity (erythrocythemia, pulmonary hypertension, or cor pulmonale)

Testing has to reflect how the patient actually desaturates, at rest, during exercise, or overnight. A single resting SpO2 reading isn’t enough if the real drop happens on exertion or during sleep. A physical therapy practice can capture that exertional drop during a pulmonary rehab session.

The CMN is retired, so the SWO carries the claim now

CMS discontinued Certificates of Medical Necessity, including Form 484 for oxygen. This applies to claims with dates of service on or after January 1, 2023. Submit one with a new claim today, and the claim gets rejected outright, not returned for correction.

A standard written order (SWO) plus supporting medical-record documentation now establishes medical necessity instead.

The SWO needs five elements: the beneficiary’s name or Medicare Beneficiary Identifier, the order date, and a description of the item, either a HCPCS code or a plain-language description. It also needs the quantity and the treating practitioner’s name or NPI, backed by a valid signature.

The medical record still has to support that order. It needs the qualifying oximetry or ABG result, plus a practitioner’s note explaining why the patient needs supplemental oxygen. Good medical forms workflows make it easier to capture all of this at the point of care. That beats chasing it down later.

Many of these orders start with a family physician. GP clinic software that captures the qualifying test at the visit keeps that record from going missing.

One exception: claims with a date of service before January 1, 2023 still follow the old CMN rules. A CMN already on file from that period remains valid for billing tied to it.

CGS Medicare administers Jurisdictions B and C. It runs a widespread pre-payment review specifically on E1390 claims billed with the N3 modifier. A late-2025 CGS probe found that 84 percent of sampled N3 claims didn’t hold up. Most failed because the N3 modifier didn’t match the documented coverage group.

Check CGS’s Jurisdiction C and Jurisdiction B announcements for the current review scope before billing N3 on an E1390 claim.

The 2026 Medicare fee schedule for HCPCS code E1390

Medicare pays for E1390 as a monthly rental under the DMEPOS fee schedule. Rates vary by MAC jurisdiction and locality. For a current dollar amount, trust only the CMS fee schedule tool and the annual DMEPOS fee schedule files.

The table below shows the structure of E1390 pricing, not the dollar figures themselves. Rates change every January and shift again for suppliers inside a Competitive Bidding Area (CBA). Always check the current file for your locality.

Download the current DMEPOS fee schedule file and filter by E1390 for the exact rate in your MAC locality. Competitive bidding areas follow the bidding round results instead of the standard fee schedule, and the two can differ substantially. You can also reference procedure code fee schedules for broader billing context.

Get the oxygen modifier right, or CGS will flag the claim

E1390 bills monthly on a CMS-1500 claim, or its electronic equivalent. The modifier attached tells the payer which coverage group the beneficiary falls into, or why the item isn’t covered. Getting this wrong is one of the fastest ways to trigger a denial or a pre-payment review.

For any new oxygen rental period starting on or after April 1, 2023, CMS requires a different modifier. Use N1, N2, or N3 instead of KX. Each modifier maps to the beneficiary’s coverage group under the Oxygen and Oxygen Equipment LCD. N1 covers Group I, N2 covers Group II, and N3 covers Group III. Group III patients qualify despite normal oxygen levels, because of a specific diagnosis. Bill the wrong one, or bill KX instead, and CMS rejects the claim as invalid, not as missing information.

For example, a beneficiary’s resting SpO2 comes back at 91%. She still qualifies under Group III criteria for a diagnosed condition such as cluster headache. Her oxygen rental starts in June 2026, so the claim needs the N3 modifier, not KX. It must be backed by documentation of her specific Group III criteria.

KX hasn’t disappeared. It still belongs on rentals that began before April 1, 2023. That includes the ongoing contents and maintenance billing tied to that same rental period. A rental that started earlier keeps using KX for its full life; it doesn’t switch to an N-modifier partway through.

One modifier you won’t need here is KF, which flags an item as an FDA Class III device. Oxygen concentrators clear the FDA through the 510(k) pathway as Class II devices, so KF doesn’t apply to E1390. If a claim template or a colleague suggests adding it, that’s worth double-checking before submission.

Every modifier here, N1, N2, N3, or legacy KX, is a supplier attestation. It tells the MAC that documentation exists and supports the coverage group billed. If CGS or another MAC audits the claim and the record doesn’t back up the modifier, expect recoupment. The MAC may also look at every other claim in that rental series.

Verify modifier requirements against your MAC’s current billing guidelines before submitting. CGS, Noridian, and Palmetto GBA each publish jurisdiction-specific coverage articles that can refine how a modifier applies. A secondary check against the code descriptor itself is worth running before submission.

Before you submit: The E1390 documentation checklist

Treat this as the floor, not the ceiling. Your MAC may want more. Digital forms can help make sure nothing is missing at the point of collection instead of after a denial arrives.

• Standard written order (SWO): all five required elements present, plus the treating practitioner’s valid signature
• Qualifying oximetry or ABG results: dated, from a certified lab or testing facility, showing SpO2 at or below 88% or a qualifying PaO2 value
• Treating practitioner’s evaluation note: explains why the patient needs supplemental oxygen and which LCD group applies
• Follow-up blood gas study (Group II and III only): performed between day 61 and day 90 of therapy and reviewed by the treating practitioner
• Legacy CMN, only if applicable: relevant solely to claims with a date of service before January 1, 2023, or ongoing billing tied to a rental that started before that date

For CGS’s pre-payment review, all of this needs to go in with the initial claim. Don’t wait for an Additional Documentation Request (ADR) to arrive. Missing even one piece typically means a denial, not a chance to submit more later. Maintaining HIPAA-compliant documentation practices matters here. Have the full record ready before submission; it isn’t optional in a jurisdiction with active pre-pay review.

Keep oxygen equipment paperwork organized, not scattered

Practice management software like Pabau helps a practice keep orders, test results, and clinical notes in one place, so your team can find what a payer asks for without a scramble.

Book a demo

E1390 vs E1391: Single port or dual port?

The code-selection question that actually matters for E1390 is E1391, not E1392. Per CMS Policy Article A52514, E1391 covers a dual delivery port concentrator shared by two different Medicare beneficiaries. It isn’t simply a two-outlet unit billed for one patient.

When that shared setup applies, only one of the two beneficiaries gets billed for E1391. That avoids billing the same physical unit twice. Bill E1390 whenever the concentrator has a single delivery port serving one beneficiary.

Billing E1391 without genuine two-beneficiary sharing, or billing E1390 for a shared dual-port unit, creates a mismatch. The documented use no longer matches the code billed. Reviewers treat that as a coding error even when it’s unintentional. Confirm whether the concentrator is actually shared before selecting the code.

Don’t fold E1392 into this comparison. E1392 is the portable oxygen concentrator, rental, a different equipment category defined by portability, not delivery ports. Portability means a battery, AC/DC adapters, a carry bag or cart, and a weight of 20 pounds or less. A patient can need E1390 or E1391 for stationary use and E1392 for portable use.

Sometimes both apply in the same month, if each is documented as medically necessary.

Related HCPCS codes for oxygen equipment

A complete oxygen therapy claim often involves more than the concentrator alone. Billing the concentrator without the right accessory codes, or the reverse, creates audit flags and potential overpayments.

The same discipline applies to other respiratory equipment. A sleep apnea oral appliance bills under E0486. A supply item without its own code often falls under A9900.

A patient using both a stationary concentrator and a portable system can have both billed in the same month. Both need to be medically necessary and documented separately. The ordering practitioner’s order and medical record need to specify both needs.

Billing one without the other, when both are actually in use, creates a documentation mismatch a reviewer will catch. Ventilator-dependent patients need the same accessory check for codes like A4483.

Common billing errors and denial reasons for HCPCS code E1390

Few competitors dig into E1390 denial patterns specifically. That’s the most useful angle for a biller who already knows the code but keeps hitting the same wall at adjudication.

• Missing or invalid SWO: the order is missing one of its five required elements, or the treating practitioner’s signature is missing or illegible. CGS and other MACs return these without a request for more information under active pre-pay review.
• Oximetry results that don’t meet the threshold: SpO2 above 88% at rest, with no supplemental testing during exercise or sleep. If the real desaturation happens on exertion, that has to be the documented qualifying test.
• Wrong modifier for the rental start date: billing KX on a new rental period that started on or after April 1, 2023, instead of N1, N2, or N3. CMS rejects these as invalid, not as missing information.
• Wrong code for the device delivered: billing E1390 for a dual-port device, or E1391 for a single-port one. The equipment specs have to match the code on the claim.
• No prior authorization or contract status in a Competitive Bidding Area: non-contract suppliers in a CBA can’t bill Medicare for E1390 at all, regardless of documentation quality.

Tracking denial reasons systematically across claims is the most practical way to find where a workflow breaks down. Practice management software with claim tracking can flag recurring denial codes. It can also trace them back to the documentation step that failed.

Pairing E1390 with the right diagnosis also matters for adjudication. Codes like J44.1, COPD with acute exacerbation, are common companions on a qualifying oxygen claim.

Conclusion

HCPCS code E1390 claims usually fail at the documentation stage, not the coding stage. Getting the code right is the easy part now. Three things decide whether a claim pays or triggers a CGS pre-payment review. The SWO has to be complete, and the qualifying test has to meet the LCD threshold. It also needs N1, N2, or N3, instead of KX, on a new rental.

Practice management software like Pabau can help a practice keep patient records, orders, and test results organized in one system. That way, nothing goes missing when a payer comes asking. Book a demo to see how it fits your practice.

Continue your research

Need a structured approach to HIPAA-compliant medical record management? HIPAA compliance for medical offices covers documentation retention, access controls, and audit readiness for DME and clinical billing teams.

Need the exact fields for a paper Medicare claim? CMS-1500 form walks through every box DME suppliers complete when billing E1390 rentals.

Billing home health alongside DME orders? G0180 covers the certification visit that often accompanies a new oxygen order.

Frequently asked questions