COVERAGE FRAMEWORK:
  NCD (National Coverage Determination): CMS national policy
    Applies nationwide, overrides LCD
    Example: NCD for CPAP therapy (240.4)
  
  LCD (Local Coverage Determination): DME MAC or carrier policy
    Applies in specific geographic jurisdiction
    Includes ICD-10-CM codes that support medical necessity
    ICD-10-CM codes must be on LCD to support claim
  
  ABN (Advance Beneficiary Notice of Noncoverage):
    Must give BEFORE service if Medicare may deny
    Patient chooses: want service and agree to pay, OR don't want
    GA modifier: ABN obtained, patient agrees to pay
    GZ modifier: expect denial, no ABN obtained

DMEMAC JURISDICTIONS:
  A: Southeast (Noridian)
  B: Midwest (CGS)
  C: Southwest (CGS)
  D: Northwest (Noridian)
  Find your MAC: based on patient's zip code, not provider's location

CERTIFICATE OF MEDICAL NECESSITY (CMN):
  Required for: oxygen, hospital beds, wheelchairs, enteral nutrition
  Physician completes and signs
  Supplier retains — does not submit with claim
  Must be on file before billing

ORTHOTIC FITTING PROCESS:
  1. Physician order with diagnosis and orthosis specification
  2. Evaluation by orthotist (O&P professional)
  3. Fabrication or fitting of device
  4. Code selection: L code for specific device type/material
  5. Bill after delivery and fitting completion
  6. Document patient education on use and care

COMMON ORTHOSES:
  L0450: Thoracic-lumbar-sacral orthosis (TLSO)
  L1900: Ankle-foot orthosis (AFO), double upright, custom
  L1906: AFO, multiligamentous ankle support, prefabricated
  L3000: Custom-molded foot orthosis (insole)
  L3671: Knee orthosis (hinged, rigid)

PROSTHETICS (L5000-L8999):
  Bill for: socket, components, fitting, training
  Functional classification: K0 (not ambulatory) to K4 (high activity)
  K level must match billed prosthesis capability
  L5100: Below knee, molded socket, shin, SACH foot (K1-K2)
  L5301: Below knee, molded socket, dynamic foot (K3-K4)
  L5987: All-terrain foot, dynamic response (K3-K4)

AMBULANCE CODE LEVELS:
  A0426: Advanced life support (ALS), non-emergency
  A0427: ALS emergency
  A0428: Basic life support (BLS), non-emergency
  A0429: BLS emergency
  A0433: Advanced life support, level 2 (ALS2)
  A0434: Specialty care transport

MODIFIERS FOR AMBULANCE:
  RH: Residence to hospital
  HR: Hospital to residence
  HH: Hospital to hospital
  SH: Scene to hospital
  NH: Nursing facility to hospital
  QL: Patient pronounced dead after ambulance called

MEDICAL NECESSITY FOR AMBULANCE:
  Patient's condition required ambulance (not just preferred)
  Documentation must show: why ambulance was necessary
  Alternative (taxi, wheelchair van) would endanger patient's health
  Most common denial reason: lack of medical necessity documentation