A0999 — Unlisted ambulance service
A0999 is a HCPCS Level II code for unlisted ambulance service. It belongs to the Transportation, Medical & Surgical Supplies, Administrative section. Whether Medicare pays it depends on the coverage rule below.
Medicare coverage: Special coverage instructions apply
There are published conditions attached to this code. Check the applicable coverage policy before billing it: the code being valid is not the same as the service being covered.
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 A0999 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 A0999
- Long descriptor
- Unlisted ambulance service
- Short descriptor
- Unlisted ambulance service
- Added
- January 1, 1987
- BETOS
- O1A
- Pricing indicator
- 57 — 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.
Other carrier priced.
Codes adjacent to A0999
HCPCS has no hierarchy — related items simply sit next to each other in the numbering. If A0999 is not quite right, the correct code is very often within a few positions of it.
- A0431Ambulance service, conventional air services, transport, one way (rotary 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
- A2001Innovamatrix ac, per square centimeter (add-on, list separately in addition to primary procedure)
- A2002Mirragen advanced wound matrix, per square centimeter (add-on, list separately in addition to primary procedure)
- A2004Xcellistem, 1 mg
- A2005Microlyte matrix, per square centimeter (add-on, list separately in addition to primary procedure)
- A2006Novosorb synpath dermal matrix, per square centimeter (add-on, list separately in addition to primary procedure)
- A2007Restrata, per square centimeter (add-on, list separately in addition to primary procedure)
- A2008Theragenesis, per square centimeter (add-on, list separately in addition to primary procedure)
- A2009Symphony, per square centimeter (add-on, list separately in addition to primary procedure)
Questions about A0999
What is HCPCS code A0999?
A0999 is a HCPCS Level II code for unlisted ambulance service. It sits in the Transportation, Medical & Surgical Supplies, Administrative section.
Does Medicare cover A0999?
The CMS HCPCS file marks A0999 as "Special coverage instructions apply". There are published conditions attached to this code. Check the applicable coverage policy before billing it: the code being valid is not the same as the service being covered.
How is A0999 paid under the physician fee schedule?
A0999 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.