Table of Contents

Introduction

A DME supplier sets a patient up on a stationary oxygen concentrator, gets a written order on file, and starts billing HCPCS E1390 monthly. A few months in, a claim gets rejected -- not because the equipment or the diagnosis was wrong, but because the wrong modifier was attached to a new rental period, or the file was missing the specific documentation that now stands in for the old paper medical necessity certificate.

E1390 identifies a specific piece of equipment, but billing it correctly depends on medical necessity documentation, current Medicare oxygen policy, and getting the details of an ongoing rental claim right over time -- not just the initial submission.

At Sirius Solutions Global, we see oxygen equipment claims run into trouble for a specific reason: the rules around modifiers and documentation for oxygen have changed in recent years, and billing teams working from outdated references keep applying the old process.

This guide covers what HCPCS E1390 represents, what documentation and medical necessity should look like, current Medicare considerations, and where these claims typically break down in 2026.

HCPCS Code:
E1390
Equipment:
Stationary oxygen concentrator, single delivery port, ≥85% O2 output
Billing Category:
Durable medical equipment (DME), typically monthly rental
Primary Focus:
Medical necessity, documentation, and coding accuracy
Reimbursement:
Varies by payer and applicable policy
Key Risk:
Documentation, modifier, or coverage-group mismatch

What Is HCPCS E1390?

HCPCS E1390 is a Level II code -- not a CPT code -- that identifies a stationary oxygen concentrator with a single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate. It's billed by the DME supplier providing the equipment, typically as a monthly rental.

It's worth distinguishing E1390 from similar codes: E1391 covers a dual-delivery-port concentrator, and E1392 covers a portable oxygen concentrator rental. Using the wrong one of these because the equipment details weren't confirmed is a common, avoidable error.

Because HCPCS codes and Medicare oxygen policy are maintained by CMS and have changed more than once in recent years, always confirm current requirements against official CMS and DME MAC guidance rather than an older article or template.

What Does E1390 Represent?

In practical terms, E1390 covers the physical concentrator unit itself -- a stationary device that pulls in room air and concentrates the oxygen for delivery through a single port. It's distinct from portable units (E1392) and from dual-port stationary units (E1391), and it's separate from the oxygen contents, tubing, and other accessories billed under their own codes.

For a billing team, the practical takeaway is that the specific unit provided needs to match the code billed -- a portable concentrator billed as E1390, or vice versa, is a documentation/coding mismatch that can trigger review even when the patient clearly needed oxygen therapy.

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E1390 Documentation Requirements

Effective for dates of service on or after January 1, 2023, CMS retired the paper Certificate of Medical Necessity (including the old oxygen CMN form) for oxygen equipment. In its place, a standard written order combined with supporting medical record documentation is what establishes medical necessity. Beyond that baseline, documentation that supports an E1390 claim generally includes:

  • A qualifying diagnosis and clinical documentation supporting the need for supplemental oxygen
  • A valid written order from the treating practitioner
  • Testing results supporting the applicable oxygen coverage group
  • Beneficiary and equipment information matching the claim
  • Supplier records, including proof of delivery where applicable
  • Documentation supporting continued medical need for ongoing rental periods
  • Any additional records required by the specific payer's current policy

Note: Documentation requirements can differ by payer, and Medicare's own requirements have changed more than once in recent years. Treat this as a general framework and confirm current specifics against the applicable payer or CMS/DME MAC guidance before submission.

Medical Necessity for Oxygen Equipment

Medical necessity is central to E1390 billing because oxygen equipment coverage under Medicare and most payers is tied to specific coverage criteria, not simply a physician's preference for the equipment. From a billing perspective, this means confirming that the clinical documentation on file -- the qualifying test results and diagnosis -- actually aligns with the coverage group the claim is billed under, before the claim goes out rather than after a denial.

This section is a billing and documentation consideration, not clinical guidance -- specific qualifying thresholds and coverage groups are defined by the applicable coverage policy and should be verified directly against current CMS/DME MAC guidance.

Medicare & E1390 Billing

Medicare billing for E1390 involves several pieces working together: beneficiary eligibility, the applicable DME MAC's current Local Coverage Determination for oxygen equipment, medical necessity documentation, supplier enrollment requirements, and accurate claim submission.

One change worth flagging: for new oxygen rental periods with dates of service on or after April 1, 2023, Medicare has required modifier N1, N2, or N3 -- corresponding to the beneficiary's coverage group under the oxygen Local Coverage Determination -- in place of the older KX modifier for those new rentals. Billing teams still defaulting to KX on new rental periods, or applying the wrong N-modifier for the coverage group, can trigger denials or claim review. Because LCDs and modifier policy can be revised, current requirements should always be confirmed against the applicable DME MAC's published guidance before submission.

E1390 Billing Workflow

1. Verify
Confirm eligibility, coverage group, and current payer requirements before equipment is set up.
2. Document
Ensure the written order and qualifying clinical documentation are on file.
3. Validate
Confirm the specific equipment matches E1390, not E1391 or E1392.
4. Submit
Bill with the correct modifier for the applicable coverage group and rental period.
5. Track
Monitor ongoing rental billing and documentation over the life of the claim.
6. Resolve
Address rejections and denials based on the specific reason, including modifier or coverage-group issues.

E1390 Reimbursement

There's no single reimbursement figure that applies to every E1390 claim. Payment depends on the payer, the applicable coverage policy, contract terms, geographic considerations, the beneficiary's specific coverage, supplier requirements, and the circumstances of the claim -- including which rental month it falls in and whether the correct modifier was applied. Sirius Solutions Global does not publish or promise a specific reimbursement amount, and any figure referenced elsewhere should be verified against the current applicable fee schedule or payer policy.

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Common E1390 Billing Mistakes

Common IssuePotential ImpactBetter Billing Practice
Incomplete documentationClaim can't demonstrate medical necessityConfirm the written order and qualifying test results are on file
Unsupported medical necessityIncreases denial riskMatch documentation to the specific coverage group being billed
Coding/documentation mismatchWrong concentrator code billedConfirm the equipment matches E1390 vs. E1391 or E1392
Incorrect beneficiary informationCauses avoidable rejectionsReview demographic and eligibility data before submission
Coverage not verifiedAssumes coverage without confirmationVerify eligibility and current coverage policy before delivery
Missing payer-specific requirementsApplies one payer's rule to anotherCheck the specific payer's current requirements
Claim submission errors, including modifier issuesWrong or missing N-modifier triggers denialConfirm the modifier matches the current rental period and coverage group
Inadequate follow-upRental billing issues go unnoticed over timeTrack claim status and documentation consistently across rental months

E1390 Denial Prevention

An experienced billing team reduces avoidable E1390 problems through consistent habits: pre-bill review of documentation and coverage group, eligibility verification, coding and modifier validation before submission, and claim edits that catch basic errors early. On the back end, categorizing denial reasons, filing corrected claims or appeals when appropriate, following up on unpaid claims on a defined schedule, and watching for recurring denial patterns all help identify whether an issue is a one-off mistake or a process gap that needs fixing.

E1390 vs. Related Oxygen Equipment Codes

Because similar-looking oxygen equipment carries different HCPCS codes, confirming the specific unit provided matters as much as confirming the diagnosis:

CodeEquipmentKey Distinction
E1390Stationary concentrator, single delivery portThe most common stationary concentrator billing code
E1391Stationary concentrator, dual delivery portSame oxygen concentration criteria, different port configuration
E1392Portable oxygen concentratorRental billing for a portable unit, not a stationary one

E1390 Billing Quick Check

E1390 Billing Risk Path

Documentation Gap
→
Claim Risk
→
Denial / Rework
→
Delayed Payment

A proactive documentation and modifier review before submission can interrupt this cycle before it starts, rather than reacting to it after a denial.

The Key Takeaway: Accurate E1390 billing depends on aligning the equipment billed with medical necessity, supporting documentation, applicable coverage rules, accurate coding and modifiers, and clean claim submission -- not just recognizing that a concentrator was provided.

Are E1390 Billing Issues Creating Unnecessary Rework?

Billing problems with E1390 often trace back to documentation gaps, an outdated modifier reference, coverage verification that wasn't completed, or inconsistent follow-up on ongoing rentals.

Sirius Solutions Global works with DME suppliers and healthcare organizations on medical billing, claims submission, denial management, A/R follow-up, and broader revenue cycle management.

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Frequently Asked Questions

HCPCS E1390 is a Level II code identifying a stationary oxygen concentrator with a single delivery port, capable of delivering 85% or greater oxygen concentration at the prescribed flow rate.
A stationary, single-delivery-port oxygen concentrator -- distinct from the dual-port E1391 and the portable E1392.
Typically as a monthly DME rental, with a modifier (N1, N2, or N3 for newer rental periods) indicating the beneficiary's coverage group.
Coverage depends on medical necessity documentation and the applicable coverage policy -- verify current requirements with CMS and the applicable DME MAC.
A valid written order, qualifying clinical/testing documentation, and accurate beneficiary and supplier records -- the paper medical necessity certificate was retired for dates of service on or after January 1, 2023.
Reimbursement varies by payer, contract, geography, and claim circumstances -- there's no single universal amount.
Common causes include incomplete documentation, an unsupported coverage group, a coding/equipment mismatch, or an incorrect or missing modifier.

Disclaimer: This article is for general informational and educational purposes only. It is not legal, coding, billing, reimbursement, or compliance advice for any specific supplier, patient, or payer contract. HCPCS codes, Medicare coverage policy, and modifier requirements are updated periodically and vary by payer, plan, state, and circumstance. Always verify current HCPCS descriptors and coverage requirements with CMS, the applicable DME MAC, and the specific payer before making billing decisions. Sirius Solutions Global makes no guarantee regarding claim approval, reimbursement amounts, coverage determinations, or denial outcomes.