DME Billing Fundamentals — Modifiers, MUEs, and the Forms You Need

May 27, 2026

Durable Medical Equipment billing is uniquely modifier-heavy. A single claim line might require five modifiers, the right rental-month indicator, and a face-to-face encounter recorded weeks before delivery. This guide covers the four most important parts of DME billing: the purchase/rental modifier system, the Standard Written Order, KX documentation, and capped rental rules.

The purchase / rental modifier system

Every DME claim line carries one of three modifiers that tell Medicare how the equipment is being provided:

  • NU — New equipment, outright purchase.
  • UE — Used equipment, outright purchase. Paid at 75% of the new purchase rate.
  • RR — Rental. Paid monthly at the rental rate, with caps that depend on the item category.

Which one applies depends on the item's classification on the DMEPOS fee schedule. Some items (like canes, walkers, and standard wheelchairs) are routine-purchase items billed with NU or UE. Others (oxygen, CPAP, hospital beds, power wheelchairs) are capped-rental items billed with RR plus a rental-month indicator.

Capped rental month indicators (KH / KI / KJ)

Most major DME categories — oxygen, CPAP/BiPAP, hospital beds, nebulizers, traction equipment, and many others — are paid as capped rentals. The supplier rents the equipment to the beneficiary, and Medicare pays a monthly rental fee for up to 13 months. After the 13th month, ownership transfers to the beneficiary.

The rental month must be indicated with one of these modifiers:

  • KH — Initial claim (first month) OR a purchase claim (use when the supplier is selling the item outright instead of renting).
  • KI — Second or third month of capped rental.
  • KJ — Fourth through fifteenth month of capped rental, OR a parenteral / enteral nutrition pump month 4 onward.

Forgetting these is a common DME denial reason. E0601-RR (CPAP, rental) alone will price incorrectly — it must be E0601-RR-KH, -RR-KI, or -RR-KJ depending on the rental month.

The KX modifier — documentation on file

For many DMEPOS items, the relevant Local Coverage Determination (LCD) specifies medical-necessity criteria — diagnosis, prior conservative therapy, clinical findings, etc. The supplier confirms that all criteria are met by appending modifier KX to the claim line.

KX is not a universal "doc on file" modifier — it is only added when the LCD explicitly requires it. The presence of KX moves the claim past the front-end edit, but the supplier remains subject to post-payment audit and must produce the documentation on request. KX cannot be applied retroactively to documentation gathered after billing.

Full modifier KX guide

The Standard Written Order (SWO)

For most DMEPOS items, a Standard Written Order from the treating physician is required before the supplier delivers the item. The SWO must include:

  • Beneficiary name and DOB
  • Date of the order
  • Description of the item ordered (including HCPCS code or sufficient description)
  • Quantity / frequency
  • Treating practitioner's name or NPI
  • Treating practitioner's signature and signature date

For certain items (power mobility devices, CGMs, oxygen, hospital beds, and others on the Master List), a face-to-face encounter within the six months before the SWO is also required, and the encounter note must be in the supplier's file.

ABN — Advance Beneficiary Notice

If the supplier expects Medicare to deny the claim as not medically necessary (for example, the item doesn't meet LCD criteria), the beneficiary should be issued an Advance Beneficiary Notice (Form CMS-R-131) before the item is delivered. The signed ABN transfers financial liability to the beneficiary if Medicare denies.

On the claim:

  • If an ABN was obtained → append modifier GA
  • If no ABN was obtained → append modifier GZ (supplier cannot bill the beneficiary if denied)
  • If the service is statutorily excluded → append modifier GY

State-level rate variation

The DMEPOS fee schedule publishes both a national Ceiling (the maximum Medicare will allow) and per-state rates for each item. Rates can vary by 20% or more between states for the same item. Always reference the rate for the supplier's jurisdiction, not the national ceiling.

DMEPOS fee schedule (national + per state)

Quick reference: a typical DME claim line

A first-month CPAP rental for a Medicare beneficiary who meets the LCD criteria looks like:

E0601-RR-KH-KX

Where E0601 is the CPAP device HCPCS code, RR = rental, KH = first month of capped rental, and KX = LCD documentation requirements met.

Month 2 changes KH to KI; months 4–13 use KJ.

Frequent denial reasons

  1. Missing rental-month modifier. RR alone won't price correctly.
  2. Missing KX where the LCD requires it. Medicare denies as missing medical necessity.
  3. SWO not on file before delivery. Supplier must hold a signed SWO before the beneficiary receives the item.
  4. Face-to-face encounter not documented or older than 6 months. Required for items on the Master List.
  5. MUE exceeded. Look up the item's MUE on its code page.
  6. Beneficiary already owns the item. Capped-rental ownership transfers after 13 months; the supplier can no longer bill rentals.

For each DME code you bill regularly, bookmark the HCPCSLookup page — it shows the fee schedule, MUE, status, and (where applicable) state-specific rates.

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