A0021 — Ambulance service, outside state per mile, transport (medicaid only)
A0021 is a HCPCS Level II code for ambulance service, outside state per mile, transport (medicaid only). It belongs to the Transportation, Medical & Surgical Supplies, Administrative section. Medicare does not pay it — see the coverage note below before you bill it.
Medicare coverage: Not payable by Medicare
Medicare does not pay this code. It may still be valid for another payer, but a Medicare claim carrying it will not be reimbursed.
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 statusI
Not valid for Medicare purposes. Medicare uses another code.
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 A0021 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
- 0 — never payable MAI 3 — Date of Service Edit: Clinical · CMS Policy
- outpatient
- 0 — never payable MAI 3 — Date of Service Edit: Clinical · CMS Policy
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 A0021
- Long descriptor
- Ambulance service, outside state per mile, transport (medicaid only)
- Short descriptor
- Outside state ambulance serv
- Added
- January 1, 1985
- BETOS
- O1A
- Pricing indicator
- 00 — Not priced by Part B
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.
Service not separately priced by Part B — not covered, bundled into another service, or used by Part A only.
Codes adjacent to A0021
HCPCS has no hierarchy — related items simply sit next to each other in the numbering. If A0021 is not quite right, the correct code is very often within a few positions of it.
- A0080Non-emergency transportation, per mile - vehicle provided by volunteer (individual or organization), with no vested interest
- A0090Non-emergency transportation, per mile - vehicle provided by individual (family member, self, neighbor) with vested interest
- A0100Non-emergency transportation; taxi
- A0110Non-emergency transportation and bus, intra or inter state carrier
- A0120Non-emergency transportation: mini-bus, mountain area transports, or other transportation systems
- A0130Non-emergency transportation: wheelchair van
- A0140Non-emergency transportation and air travel (private or commercial) intra or inter state
- A0160Non-emergency transportation: per mile - case worker or social worker
Questions about A0021
What is HCPCS code A0021?
A0021 is a HCPCS Level II code for ambulance service, outside state per mile, transport (medicaid only). It sits in the Transportation, Medical & Surgical Supplies, Administrative section.
Does Medicare cover A0021?
The CMS HCPCS file marks A0021 as "Not payable by Medicare". Medicare does not pay this code. It may still be valid for another payer, but a Medicare claim carrying it will not be reimbursed.
How is A0021 paid under the physician fee schedule?
A0021 carries PFS status code I. Not valid for Medicare purposes. Medicare uses another code.