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Modifier MS

Maintenance and Servicing of DME

Modifier MS identifies a six-month maintenance and servicing fee for eligible durable medical equipment, including reasonable and necessary parts and labor not covered by a manufacturer or supplier warranty.

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Related Modifiers

Modifier RR

Rental Equipment

Modifier RB

Replacement Parts

Modifier RA

Equipment Replacement

When to Use

When NOT to Use

Eligible Equipment

MS vs. RR & RB

Billing Example

Servicing Rules

Documentation

Errors & Denials

FAQs

What Is Modifier MS?

Modifier MS is a HCPCS Level II modifier used to report eligible maintenance and servicing of durable medical equipment (DME).

Its official description is “Six month maintenance and servicing fee for reasonable and necessary parts and labor which are not covered under any manufacturer or supplier warranty.”

Modifier MS is particularly important for certain oxygen equipment and infusion pumps that qualify for maintenance and servicing payments under Medicare.

Unlike modifiers identifying equipment rental or purchase, MS identifies a maintenance and servicing payment associated with eligible equipment.

Important: Modifier MS does not authorize separate reimbursement for all DME repairs or routine maintenance. Coverage depends on the equipment category, applicable payment period, warranty status, and payer requirements.

Quick Reference

Modifier: MS

Type: Service Fee

Category: DMEPOS

Meaning: Maintenance & Servicing

Billing: Eligible Maintenance

Warranty: Not Covered

When to Use Modifier MS

Eligible Oxygen Equipment: Report MS for qualifying maintenance and servicing of certain oxygen concentrators and transfilling equipment after the applicable Medicare rental period.

Infusion Pump Servicing: Use MS for eligible maintenance and servicing of certain enteral and parenteral nutrition pumps after the initial rental period, subject to the applicable payment rules.

Required Service Visits: For Medicare oxygen equipment, the supplier must perform the qualifying maintenance and servicing visit before billing.

Outside Warranty Coverage: The maintenance or servicing must satisfy applicable coverage requirements and must not be reimbursable under an existing manufacturer or supplier warranty.

Eligible Billing Period: Submit MS only when the required interval has elapsed and the equipment qualifies for a maintenance and servicing payment.

Important: MS is not a general repair modifier. Its use is limited to equipment and maintenance arrangements recognized by the payer.

When NOT to Use Modifier MS

Initial Oxygen Rental Period: Do not separately bill MS during the first 36 months of Medicare oxygen equipment rental.

Initial Infusion Pump Rental: Do not report MS during the initial 15-month rental period for enteral or parenteral nutrition pumps.

Warranty-Covered Services: Do not bill separately for services covered by an applicable manufacturer or supplier warranty.

Ineligible Equipment: Do not use MS for equipment categories that do not qualify for the applicable maintenance and servicing payment.

Unperformed Service Visits: Do not bill an oxygen equipment maintenance fee when the required service visit has not occurred.

Routine Equipment Replacement: MS does not identify replacement of an entire DME item.

Important: A maintenance request or equipment inspection does not automatically qualify for a separately payable MS claim.

Equipment Eligible for Modifier MS

Medicare maintenance and servicing rules vary by equipment category. Two important applications involve oxygen equipment and nutrition pumps.

Oxygen Concentrators and Transfilling Equipment

Certain oxygen equipment may qualify for a six-month maintenance and servicing payment after the initial 36-month rental period.

Applicable HCPCS codes include:

E1390: Oxygen concentrator, single delivery port
E1391: Oxygen concentrator, dual delivery port
E0433: Portable liquid oxygen transfilling system
K0738: Portable gaseous oxygen transfilling system

For eligible equipment, Medicare generally allows a maintenance and servicing payment no more frequently than once every six months after the applicable waiting period.

Separate MS payments are not available for gaseous or liquid oxygen equipment outside the qualifying categories.

Enteral and Parenteral Nutrition Pumps

Certain nutrition pumps may qualify for maintenance and servicing payments after the initial 15-month rental period.

Enteral Pumps: Eligible maintenance and servicing payments may begin six months after the final rental payment and occur no more frequently than every six months.

Parenteral Pumps: Eligible maintenance and servicing payments may begin three months after the final rental payment and occur no more frequently than every three months.

These pump-specific payment intervals differ from the standard six-month oxygen equipment schedule.

Important: Equipment eligibility and reimbursement requirements must be verified before submitting MS.

Modifier MS vs. RR and RB

These modifiers identify different DME billing circumstances.

Modifier MS – Maintenance and Servicing: Identifies an eligible maintenance and servicing fee under the applicable equipment payment rules.

Modifier RR – Rental Equipment: Identifies equipment furnished on a rental basis. Maintenance costs are generally included in rental payments unless a specific exception applies.

Modifier RB – Replacement Part: Identifies replacement of a part of DME furnished as part of a repair when permitted under the applicable billing rules.

Key Difference: MS identifies an eligible servicing payment, RR identifies rental equipment, and RB identifies a replacement component used during a repair.

For example, replacing a broken component on beneficiary-owned equipment may require different billing codes than a scheduled maintenance and servicing visit for qualifying oxygen equipment.

Billing Example

A Medicare beneficiary continues using an oxygen concentrator after completing the initial 36-month rental period.

Six months after the rental period ends, the supplier performs an eligible maintenance and servicing visit. The equipment is not covered by a warranty that would delay the payment, and all Medicare requirements are satisfied.

Example – Oxygen Concentrator Maintenance:

E1390-MS

Claim Details:

HCPCS Code: E1390 – Oxygen concentrator, single delivery port

Modifier: MS – Maintenance and Servicing

Equipment: Oxygen Concentrator

Service: Eligible Maintenance Visit

Billing Period: After Initial 36-Month Rental

Documentation: Service Visit Record

Important: Medicare permits payment for eligible oxygen equipment maintenance and servicing no more frequently than once during an applicable six-month period, even when the beneficiary uses multiple qualifying pieces of oxygen equipment.

Medicare Maintenance and Servicing Rules

Medicare establishes specific payment requirements for maintenance and servicing of certain DME categories.

36-Month Oxygen Rental Period

Maintenance and servicing are included in the initial 36-month oxygen equipment rental payments. Separate MS reimbursement is not permitted during this period.

Six-Month Maintenance Interval

For qualifying oxygen equipment, the first eligible maintenance payment may occur no sooner than six months after the end of the 36-month rental period or the end of an applicable warranty, whichever is later.

Required Supplier Visit

The supplier must actually visit the beneficiary to inspect and service the equipment. Multiple visits during one six-month period do not establish eligibility for multiple MS payments.

2026 Medicare Payment Amount

For calendar year 2026, the Medicare maintenance and servicing payment amount for qualifying oxygen concentrators and transfilling equipment is $89.58.

This amount applies to the specified Medicare oxygen equipment payment category and should not be assumed to apply to all equipment billed with MS.

Warranty Restrictions

Services covered by a manufacturer or supplier warranty are not separately payable under MS.

Important Billing Rule: The six-month servicing payment is a specific Medicare benefit, not a general authorization to charge for routine DME maintenance.

Documentation Requirements

Modifier MS claims must demonstrate that the equipment qualifies for maintenance and servicing and that the service satisfies the applicable coverage requirements.

Equipment Identification: Document the equipment's HCPCS code, model, and identifying information.

Rental History: Maintain records establishing when the initial rental period ended.

Service Date: Record the actual date of the maintenance and servicing visit.

Service Description: Describe the inspection, maintenance, or servicing performed.

Warranty Status: Verify whether the equipment or service remains covered under a manufacturer or supplier warranty.

Continued Medical Need: Maintain supporting documentation demonstrating that the equipment remains medically necessary under applicable coverage requirements.

Documentation Checklist:

Eligible equipment verified
Initial rental period completed
Required billing interval satisfied
Maintenance visit documented
Warranty coverage reviewed
Continued medical need supported

Important: Documentation must establish that the service occurred and that the equipment qualifies for the applicable maintenance and servicing payment.

Frequently Asked Questions

Can Modifier MS be billed if the equipment is functioning properly?

For qualifying oxygen equipment, an eligible maintenance and servicing visit may be payable even when the equipment has not broken down. The supplier must perform the required service, satisfy the applicable timing rules, and maintain supporting documentation.

Can Modifier MS be used for equipment owned by the beneficiary?

Not automatically. Medicare has separate rules for maintenance and repairs of beneficiary-owned equipment. Modifier MS is appropriate only when the equipment and service qualify under the applicable maintenance and servicing payment policy.