A0431 — Ambulance service, conventional air services, transport, one way (rotary wing)
A0431 is a HCPCS Level II code for ambulance service, conventional air services, transport, one way (rotary wing). It belongs to the Transportation, Medical & Surgical Supplies, Administrative section. Whether Medicare pays it depends on the coverage rule below.
Medicare coverage: Carrier judgment
Coverage is decided by your Medicare contractor, not by national policy. Whether this is paid depends on the LCD for your jurisdiction and on what the documentation supports.
From the coverage field of the CMS Alpha-Numeric HCPCS File, release 2026Q3-Jul. This states Medicare’s position on the code, not on your particular claim.
Physician fee schedule statusX
Statutory exclusion. The item or service is not within the statutory definition of 'physician services', so the fee schedule never pays it.
Global period: XXX
Want the dollar amount for your locality? The fee calculator applies your GPCI and the current conversion factor.
Medically Unlikely Edits — units per day
The most units of A0431 Medicare will pay on one date of service. Bill more on a single line and it is denied. The limit is not the same in every setting, so the row that matters is the one matching the claim you are building.
- practitioner
- 1 unit MAI 3 — Date of Service Edit: Clinical · Clinical: Data
- outpatient
- 1 unit MAI 3 — Date of Service Edit: Clinical · Clinical: Data
The adjudication indicator decides whether exceeding the limit is worth appealing at all: MAI 1 is a line edit you can support with documentation, MAI 3 is a date-of-service edit that is also appealable, and MAI 2 is absolute — no documentation overrides it. CMS MUE 2026Q3.
The CMS record for A0431
- Long descriptor
- Ambulance service, conventional air services, transport, one way (rotary wing)
- Short descriptor
- Rotary wing air transport
- Added
- January 1, 2001
- BETOS
- O1A
- Pricing indicator
- 52 — Other
The official wording. This is what the code means.
CMS's 28-character form, which is what shows up on a remittance advice.
When CMS introduced the code.
Berenson-Eggers Type of Service — CMS's own analytic grouping.
Reasonable charge.
Codes adjacent to A0431
HCPCS has no hierarchy — related items simply sit next to each other in the numbering. If A0431 is not quite right, the correct code is very often within a few positions of it.
- A0422Ambulance (als or bls) oxygen and oxygen supplies, life sustaining situation
- A0424Extra ambulance attendant, ground (als or bls) or air (fixed or rotary winged); (requires medical review)
- A0425Ground mileage, per statute mile
- A0426Ambulance service, advanced life support, non-emergency transport, level 1 (als 1)
- A0427Ambulance service, advanced life support, emergency transport, level 1 (als 1 - emergency)
- A0428Ambulance service, basic life support, non-emergency transport, (bls)
- A0429Ambulance service, basic life support, emergency transport (bls-emergency)
- A0430Ambulance service, conventional air services, transport, one way (fixed wing)
- A0432Paramedic intercept (pi), rural area, transport furnished by a volunteer ambulance company which is prohibited by state law from billing third party payers
- A0433Advanced life support, level 2 (als 2)
- A0434Specialty care transport (sct)
- A0435Fixed wing air mileage, per statute mile
- A0436Rotary wing air mileage, per statute mile
- A0888Noncovered ambulance mileage, per mile (e.g., for miles traveled beyond closest appropriate facility)
- A0998Ambulance response and treatment, no transport
- A0999Unlisted ambulance service
Questions about A0431
What is HCPCS code A0431?
A0431 is a HCPCS Level II code for ambulance service, conventional air services, transport, one way (rotary wing). It sits in the Transportation, Medical & Surgical Supplies, Administrative section.
Does Medicare cover A0431?
The CMS HCPCS file marks A0431 as "Carrier judgment". Coverage is decided by your Medicare contractor, not by national policy. Whether this is paid depends on the LCD for your jurisdiction and on what the documentation supports.
How is A0431 paid under the physician fee schedule?
A0431 carries PFS status code X. Statutory exclusion. The item or service is not within the statutory definition of 'physician services', so the fee schedule never pays it.