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HCPCS A0431 · Level II · A code

A0431: Ambulance service, conventional air services, transport, one way (rotary wing), HCPCS Level II A code

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: HCPCS Level II file: October 2026 (effective October 1, 2026); PFS relative value file: RVU26D, released August 26, 2026 (effective October 1, 2026); NCCI MUE tables: 2026 Q4 (effective October 1, 2026); NCCI PTP edits: v323r0 (2026 Q4) (effective October 1, 2026); OPPS Addendum B: October 2026 (effective October 1, 2026). Next CMS release: January 1, 2027 (quarterly update) for the HCPCS Level II file and NCCI MUE tables and NCCI PTP edits and OPPS Addendum B; RVU27A with the CY2027 PFS final rule, effective January 1, 2027 for the PFS relative value file.

Key facts for A0431

Medicare payment
no PFS amount
PFS status X; OPPS SI A: paid under another fee schedule or system
Coverage code
C
carrier judgment, so the Medicare contractor decides coverage
Practitioner MUE
1
MAI 3
OPPS status
SI A
Services not paid under OPPS; paid under fee schedule or other payment system
NCCI PTP pairs
0
practitioner file
LCDs and articles
0 / 0

TL;DR

A0431 is a Level II code from the A section (transportation, medical and surgical supplies, administrative, miscellaneous and investigational), in use since 2001: "Ambulance service, conventional air services, transport, one way (rotary wing)". The physician fee schedule lists A0431 with status X (statutory exclusion: not a physician service under the fee schedule), so the PFS carries no national amount for it. Its OPPS status indicator is A, which the I/OCE table defines as "Services not paid under OPPS; paid under fee schedule or other payment system": Medicare pays A0431 under a fee schedule or payment system other than OPPS. Its 2026 Q4 MUEs per date of service: practitioner 1 (MAI 3, Clinical: Data); hospital outpatient 1 (MAI 3, Clinical: Data). A0431 appears in no active LCD or billing and coding article, so coverage follows HCPCS coverage code C (carrier judgment, so the Medicare contractor decides coverage) and any NCD. HCPCS record: BETOS O1A (ambulance); pricing indicator 52; type of service D (ambulance). 7 other active codes open with "Ambulance service"; related codes: A0430, A0429, A0428, A0427.

A0431 descriptor and code status

The October 2026 HCPCS Level II file describes A0431 as “Ambulance service, conventional air services, transport, one way (rotary wing)”. It sits in the A section (transportation, medical and surgical supplies, administrative, miscellaneous and investigational), listed with the other A codes. Although searches often call it the "A0431 CPT code", A0431 is a HCPCS Level II code maintained by CMS, not an AMA CPT code; both go in the same procedure-code field on the claim.

HCPCS file attributes of A0431
FieldValue
Short descriptorRotary wing air transport
Added to HCPCS2001-01-01
Last actionN (no maintenance), effective 2001-01-01
Coverage codeC: carrier judgment, so the Medicare contractor decides coverage
Pricing indicator52: reasonable charge
BETOS categoryO1A: ambulance
Type of serviceD: ambulance

Medicare payment for A0431

The physician fee schedule lists A0431 with status X (statutory exclusion: not a physician service under the fee schedule), so the PFS carries no national amount for it. Its OPPS status indicator is A, which the I/OCE table defines as "Services not paid under OPPS; paid under fee schedule or other payment system": Medicare pays A0431 under a fee schedule or payment system other than OPPS. The amounts below are national figures from the October 2026 CMS files; the contractor applies the locality, rural or state adjustment and the beneficiary's cost sharing.

Physician fee schedule (RVU26D)

Status X: statutory exclusion: not a physician service under the fee schedule. Global period XXX (global surgery concept does not apply); PC/TC indicator 9 (professional/technical concept does not apply).

Hospital outpatient (OPPS Addendum B)

Status indicator A (Services not paid under OPPS; paid under fee schedule or other payment system), with no separate OPPS payment rate.

Medically Unlikely Edits for A0431

Its 2026 Q4 MUEs per date of service: practitioner 1 (MAI 3, Clinical: Data); hospital outpatient 1 (MAI 3, Clinical: Data). The practitioner MUE is a date-of-service clinical edit: units above the limit deny but can be paid on appeal with documentation.

MUE values for A0431 by setting
SettingMUE (units/DOS)MAICMS rationale
Practitioner services13 Date of Service Edit: ClinicalClinical: Data
Facility outpatient hospital13 Date of Service Edit: ClinicalClinical: Data

The MUE lookup for A0431 shows every setting next to any other code on the same claim.

NCCI edits and add-on rules

No active practitioner PTP pair lists A0431 in v323r0.

A0431 is neither an add-on code nor a designated primary code in the 2026 Q4 NCCI add-on edit file.

Pair counts show exposure, not the answer for one claim. Check A0431 against a second code to see whether the pair bundles and whether a modifier can separate the services.

Medicare coverage policies for A0431

No current LCD or billing and coding article lists A0431. The HCPCS coverage code C means carrier judgment, so the Medicare contractor decides coverage, and any National Coverage Determination for the service still applies.

Denials to expect on A0431

CARC 50 · N115

the service is not reasonable and necessary for the diagnosis on the claim

CARC 151 · N362

units of A0431 exceed the practitioner MUE of 1 per date of service

CARC 4

the modifier reported is inconsistent with the code

CARC 16

the claim lacks information needed to adjudicate the line, such as an order, NPI or required modifier

Where QuickIntell fits for A0431 claims

QuickCode supports qualified coder review of units, modifiers and NCCI pairs for A0431 before the claim leaves, and QuickRCM carries claim readiness and the denial follow-up when an edit or coverage policy is missed.

See QuickCode for coder reviewSee QuickRCM for denial follow-upBook a meeting

Frequently asked questions: HCPCS A0431

What does HCPCS code A0431 describe?

"Ambulance service, conventional air services, transport, one way (rotary wing)" (short descriptor "Rotary wing air transport"), in the A section (transportation, medical and surgical supplies, administrative, miscellaneous and investigational). Added 2001-01-01.

Is A0431 a CPT code?

No. A0431 is a CMS HCPCS Level II code; CPT codes are the AMA's five-character set. Searches for "A0431 CPT code" mean this Level II code.

What does Medicare pay for A0431?

The physician fee schedule lists A0431 with status X (statutory exclusion: not a physician service under the fee schedule), so the PFS carries no national amount for it. Its OPPS status indicator is A, which the I/OCE table defines as "Services not paid under OPPS; paid under fee schedule or other payment system": Medicare pays A0431 under a fee schedule or payment system other than OPPS.

How many units of A0431 can be billed per day?

Its 2026 Q4 MUEs per date of service: practitioner 1 (MAI 3, Clinical: Data); hospital outpatient 1 (MAI 3, Clinical: Data). For the practitioner MUE (MAI 3), units above 1 deny for the day but can be paid on appeal with documentation; denials arrive as CARC 151.

Does Medicare cover A0431?

A0431 appears in no active LCD or billing and coding article, so coverage follows HCPCS coverage code C (carrier judgment, so the Medicare contractor decides coverage) and any NCD.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

This page is an operational reference compiled from CMS publications: the HCPCS Level II file, the physician, DMEPOS and clinical laboratory fee schedules, OPPS and ASC addenda, NCCI MUE, PTP and add-on edit tables and the Medicare Coverage Database. Amounts are Medicare national figures before locality and state adjustment; Medicaid and commercial payers set their own. CPT codes are shown as numbers only; CPT descriptors are copyright AMA. Nothing here is legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.