Joint DME MAC Publication
Posted April 23, 2026

In April 2003 the Centers for Medicare & Medicaid Services (CMS) issued a National Coverage Determination (NCD) establishing coverage for functional electrical stimulation (FES) to enable spinal cord injured (SCI) patients to walk (see National Coverage Determinations Manual 100-03 Chapter 1, Part 2, Section 160.12).

Functional electrical stimulation is a technique that uses electrical impulses to activate paralyzed or weak muscles in precise sequence. The FES device transmits these electrical impulses via surface electrodes in the same manner as neuromuscular electrical stimulation (NMES). For example, through selective and sequential stimulation of various lower extremity muscle groups, FES can enable spinal cord injured (SCI) patients to walk.

Coverage of NMES (other than FES) to treat muscle atrophy is limited to the treatment of patients with disuse atrophy where the nerve supply to the muscle is intact, including brain, spinal cord and peripheral nerves and other non-neurological reasons for disuse atrophy. There has been no change in NCD coverage criteria when NMES is used to treat disuse atrophy.

Coverage of FES

Medicare will consider coverage of FES for SCI patients who have completed a training program consisting of at least 32 physical therapy sessions with the device, over a period of three months.

Per the CMS NCD 160.12, coverage for FES to enhance walking will be limited to SCI patients with ICD-10-CM codes G04.1 -Tropical spastic paraplegia, G82.20 - Paraplegia, unspecified, G82.21 - Paraplegia, complete, G82.22 - Paraplegia, incomplete, and with all of the following characteristics:

1. Persons with intact lower motor units (L1 and below) (both muscle and peripheral nerve); and,
2. Persons with muscle and joint stability for weight bearing at upper and lower extremities that can demonstrate balance and control to maintain an upright support posture independently; and,
3. Persons that demonstrate brisk muscle contraction to NMES and have sensory perception of electrical stimulation sufficient for muscle contraction; and,
4. Persons that possess high motivation, commitment and cognitive ability to use such devices for walking; and,
5. Persons that can transfer independently and can demonstrate standing independently for at least three minutes; and,
6. Persons that can demonstrate hand and finger function to manipulate controls; and,
7. Persons with at least six-month post recovery spinal cord injury and restorative surgery; and,
8. Persons without hip and knee degenerative disease and no history of long bone fracture secondary to osteoporosis; and,
9. Persons who have demonstrated a willingness to use the device long-term.

FES used to enhance walking for SCI patients with any of the following conditions, will not be covered:

1. Presence of cardiac pacemakers;
2. Severe scoliosis or severe osteoporosis;
3. Irreversible contracture;
4. Autonomic dysreflexia; or
5. Skin disease or cancer at area of stimulation.

Indications for FES other than to enable SCI patients to walk will be denied as not medically necessary.

The only settings where therapists with the sufficient skills to provide these services are employed are inpatient hospitals, outpatient hospitals, comprehensive outpatient rehabilitation facilities, and outpatient rehabilitation facilities. The physical therapy necessary to perform this training must be part of a one-on-one training program.

HCPCS Coding

Two codes are used to bill for FES:

• E0764 - FUNCTIONAL NEUROMUSCULAR STIMULATION, TRANSCUTANEOUS STIMULATION OF SEQUENTIAL MUSCLE GROUPS OF AMBULATION WITH COMPUTER CONTROL, USED FOR WALKING BY SPINAL CORD INJURED, ENTIRE SYSTEM, AFTER COMPLETION OF TRAINING PROGRAM
• E0770 - FUNCTIONAL ELECTRICAL STIMULATOR, TRANSCUTANEOUS STIMULATION OF NERVE AND/OR MUSCLE GROUPS, ANY TYPE, COMPLETE SYSTEM, NOT OTHERWISE SPECIFIED

Note that HCPCS codes E0764 and E0770 represent the "entire system" for the FES devices. Therefore, individual components such as walkers, crutches, or other supplies must not be billed separately.

Manufacturers of products billed with code E0770 must have the code(s) verified by the Pricing, Data Analysis, and Coding (PDAC) contractor. Currently, the only products that are coded E0770 are:

• WalkAide (Innovative Neurotronics)
• Odstock DROP FOOT STIMULATOR PACE (Odstock Medical LTD/Boston Brace)
• NESS L300 and H200 devices (Bioness Inc.)
• Deluxe Digital Electronic Muscle Stimulator (Drive medical)
• Regrasp (Rehabtronics Inc.)

Code E0764 does not require code verification by the PDAC; however, currently the only product that is coded E0764 is the Parastep I (Sigmedics).

Modifiers

GA, GY, GZ, KF, and SC

In the absence of an LCD, reasonable and necessary (R&N) requirements are detailed in the CMS NCD 160.12 (Neuromuscular Electrical Stimulation (NMES)). The proper use of modifiers indicates whether the beneficiary meets the R&N requirements in the NCD. These modifiers indicate whether or not the applicable payment criteria are met (SC 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 GA, GY, GZ, or SC modifier will be rejected as missing information.

SC - Medically necessary service or supply
The SC modifier must be appended to an FES device claim when all of the statutory and R&N requirements outlined in NCD 160.12 have been met. Suppliers are not required to secure all the required documentation prior to claim submission, however, appending the SC modifier to the FES device code 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 R&N, Advance Beneficiary Notice of Non-coverage [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. Functional electrical stimulation devices are 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 R&N (expected to be denied as not R&N, 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 R&N criteria are not met, either the GA or GZ modifier is appropriate based upon ABN status.

KF - Item designated by FDA as class III device
The KF modifier (ITEM DESIGNATED BY FDA AS CLASS III DEVICE) indicates that the claim line includes a device classified by the Food and Drug Administration (FDA) as "Class III." Classification of a device as "Class III" is specific to the device. It is not specific to the HCPCS code that describes the device. If the device is Class III, then the supplier must append the KF modifier. If the device is not Class III, then the supplier must not append the KF modifier.

Functional electrical stimulator devices coded E0764 are classified by the FDA as Class III devices; therefore, all claims for code E0764 must include the KF modifier. Claim lines billed without a KF modifier will be rejected as missing information.

For questions about correct coding, contact the PDAC HCPCS Helpline at (877) 735-1326 during the hours of 9:30 a.m. to 5:00 p.m. ET, Monday through Friday. You may also visit the PDAC website to chat with a representative or select the Contact Us button at the top of the PDAC website for email, FAX, or postal mail information.

Please refer to the Standard Documentation Requirements for All Claims Submitted to DME MACs (A55426) for additional coding and documentation requirements.

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