Medicare Carrier and Outpatient Files: Identifying Ambulance Services

Purpose

Claims for ambulance services are found in both the Carrier and the Outpatient claims data. This article describes how to identify ambulance services.

Current Version Date:
01/31/2017
Billing for Ambulance Services

Ambulance services are billed to Medicare using HCPCS codes; the specific ambulance codes Medicare covers are listed in the Ambulance Fee Schedule. Ambulance Fee Schedules are updated annually. The codes in use between 2006 and 2017 are listed as a quick guide, but the authoritative references are the Ambulance Fee Schedules for each year of interest.  

HCPCS Code Description
A0425 Ground mileage, per statute mile
A0426 Ambulance service, advanced life support, non-emergency transport, level 1 (als 1)
A0427 Ambulance service, advanced life support, emergency transport, level 1 (als1-emergency)
A0428 Ambulance service, basic life support, non-emergency transport, (bls)
A0429 Ambulance service, basic life support, emergency transport (bls-emergency)
A0430 Ambulance service, conventional air services, transport, one way (fixed wing)
A0431 Ambulance service, conventional air services, transport, one way (rotary wing)
A0432 Paramedic intercept (pi), rural area, transport furnished by a volunteer ambulance company which is prohibited by state law from billing third party payers
A0433 Advanced life support, level 2 (als 2)
A0434 Specialty care transport (sct)
A0435 Fixed wing air mileage, per statute mile
A0436 Rotary wing air mileage, per statute mile
Table 1: Codes to Bill Ambulance Services, 2006-2017
Claims files

Claims for ambulance transports are found in the Carrier and the Outpatient claims data. One ambulance trip will generate either a Carrier or an Outpatient claim, but not both. Claims submitted by hospital-based ambulance providers are found in the Outpatient claims data. Claims from non-hospital-based ambulance providers are found in the Carrier data. Approximately 95% of ambulance claims are located in the Carrier data.

Components of Ambulance Billing

There are two components of ambulance billing:

  • The service
  • The mileage

An individual claim will contain a HCPCS code for the service and a HCPCS code for the mileage. This means there will be at least two line items (Carrier) or two revenue center (Outpatient) records submitted for each ambulance claim. 

Multiple trips on one day

It is possible for a patient to have multiple ambulance trips on one day.  At least 20% of ambulance billing includes multiple trips for a beneficiary on one date. The most common scenario is transportation to and from an ESRD facility. Multiple trips may be billed on one claim, or there may be separate claims for each trip.

HCPCS modifiers specific to ambulance services

Ambulance claims contain origin and destination HCPCS modifier codes. The first position of the modifier code is the point of origin and the second position is the destination:

D = Diagnostic or therapeutic site other than P or H when these are used as origin codes
E = Residential, domiciliary, custodial facility (other than 1819 facility)
G = Hospital-based ESRD facility
H = Hospital
I = Site of transfer (e.g. airport or helicopter pad) between modes of ambulance transport
J = Freestanding ESRD facility
N = Skilled nursing facility
P = Physician’s office
R = Residence
S = Scene of accident or acute event
X = Intermediate stop at physician’s office on way to hospital (destination code only)

For example, “RH” indicates a patient was transported from a residence to the hospital.  “HR” indicates the patient was transported from a hospital to a residence.  “HH” indicates the patient was transported from one hospital to another. These modifiers can be useful to identify multiple trips in one day when the origin and destination codes of each trip are different.

 

For additional information regarding the billing of ambulance services, including the billing of multiple trips in one day, please see:

CMS Ambulance Services Center 
Ambulance Chapter of the Medicare Claims Processing Manual