Correct Coding - Submitting Oxygen Claims with Modifiers KX, GA, GY, and GZ - Revised - JA DME

Joint DME MAC Publication
Posted on December 29, 2022

With the publication of the revised Oxygen and Oxygen Equipment Local Coverage Determination (LCD L33797), the DME MACs remind suppliers of the proper use of modifiers to indicate whether or not the beneficiary meets the reasonable and necessary requirements in the LCD. These modifiers indicate whether the applicable payment criteria are met (KX modifier), and provide additional information related to the coverage and/or liability (GA, GY and GZ modifiers) when the policy criteria are not met. The use of these modifiers is mandatory. Claim lines billed without a KX, GA, GY or GZ modifier will be rejected as missing information.

KX - Requirements specified in the medical policy have been met
The KX modifier must be appended to an oxygen or oxygen equipment claim when all the statutory and reasonable and necessary (R&N) requirements have been met. Suppliers are not required to secure all the required documentation prior to claim submission, however, appending the KX modifier to each of the oxygen codes billed serves as an attestation by the supplier that the requirements for its use have been met.

GA - Waiver of liability (expected to be denied as not reasonable and necessary, ABN on file)
When a Medicare claim denial is expected because an item or service does not meet the R&N criteria, the supplier must issue an ABN to the beneficiary before furnishing the item or service. When the beneficiary accepts financial responsibility, and signs a valid ABN, the supplier submits the claim to Medicare appending modifier GA to each corresponding HCPCS code. Modifier GA indicates that the supplier has a waiver of liability statement on file. Modifier GA must not be submitted if a valid ABN is not issued. Claims submitted with the GA modifier will receive a medical necessity denial holding the beneficiary liable.

GY - Item or service statutorily excluded or does not meet the definition of any Medicare benefit
The GY modifier indicates that an item or service is statutorily excluded or does not meet the definition of any Medicare benefit. Oxygen and oxygen equipment is covered under the Durable Medical Equipment benefit (Social Security Act §1861(s)(6)). Claims submitted with the GY modifier will be denied as statutorily noncovered holding the beneficiary liable for the excluded services.

GZ - Item or service not reasonable and necessary (expected to be denied as not reasonable and necessary, no ABN on file)
When a Medicare claim denial is expected because an item or service does not meet the R&N criteria, the supplier is expected to issue an ABN to the beneficiary. If the supplier chooses to accept liability for the expected denial, the supplier must append the GZ modifier to each corresponding HCPCS code. Modifier GZ indicates that the supplier does not have a waiver of liability statement on file. Claims submitted with the GZ modifier will receive a medical necessity denial holding the supplier liable.

Proper selection of the correct G modifier requires an assessment of the possible cause for a denial. Some criteria are based upon statutory requirements. Failure to meet a statutory requirement justifies the use of the GY modifier. When Reasonable and Necessary (R&N) criteria are not met, either the GA or GZ modifier is appropriate based upon Advance Beneficiary Notice of Noncoverage (ABN) status.

Additional information on the coverage, coding and documentation requirements for oxygen may be found in the Oxygen and Oxygen Equipment Local Coverage Determination (L33797 ) and related Policy Article (A52514 ) on the DME MAC web sites and the CMS Medicare Coverage Database.

Note: The DME MACs are aware of a pending CMS HCPCS Workgroup request for the creation of new N-modifiers to replace the KX modifier in the Oxygen and Oxygen Equipment LCD. Until these new modifiers are implemented and incorporated into the Oxygen and Oxygen Equipment LCD, suppliers should continue to follow the guidance provided above for the use of the KX, GA, GY and GZ modifiers.

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