July 17, 2025

Medical Coding Ambulance Services

AAPC | Certification | Certified Medical Coder | CPC | Medical Coding
By Janine Mothershed

Ambulance Coding and Billing Guidelines and Tips

Ambulance services play a critical role in emergency and non-emergency medical transportation. Accurate coding and billing for ambulance services ensures compliance with payer regulations and proper reimbursement. This article provides key guidelines and practical tips for medical coders and billers who handle ambulance claims.

Ambulance Service Levels

Ambulance services are categorized by the level of care provided. Common levels include:

  • Basic Life Support (BLS): Includes non-invasive procedures such as CPR, splinting, and oxygen.

    • BLS Emergency (A0429)

    • BLS Non-Emergency (A0428)

  • Advanced Life Support (ALS): Involves services provided by a paramedic, such as IV therapy or cardiac monitoring.

    • ALS1 Non-Emergency (A0426)

    • ALS1 Emergency (A0427)

    • ALS2 (A0433) – For advanced procedures like intubation, drug administration, or more than one ALS intervention.

  • Specialty Care Transport (SCT) (A0434): Used for critically ill or injured patients requiring medical services beyond ALS2.

  • Air and Water Transport:

    • Fixed Wing (A0430)

    • Rotary Wing (Helicopter) (A0431)

Key Billing Components

Each ambulance claim typically includes:

  • Base Rate Code: Reflects the level of service (e.g., A0429 for BLS Emergency).

  • Mileage Code (A0425): Based on loaded miles (patient onboard), rounded up to the nearest tenth of a mile.

  • Modifiers: Two-letter HCPCS modifiers are required to identify the origin and destination of the transport.

Common Modifiers:

  • P – Physician’s office

  • H – Hospital

  • S – Scene of accident

  • R – Residence

  • D – Diagnostic or therapeutic site

Example: RH = transport from residence to hospital

Documentation Requirements

Thorough documentation is essential. Medicare and other payers require proof that ambulance transport was medically necessary and that other means of transportation were contraindicated.

Documentation should include:

  • Patient’s condition

  • Medical necessity for transport

  • Treatments administered en route

  • Reason for specific level of service

  • Origin and destination addresses

Medical Necessity and Coverage

Ambulance services are only covered when other transportation methods are not safe due to the patient’s medical condition. Non-covered services include transports for convenience, patient/family preference, or lack of transportation.

Tips for Accurate Ambulance Coding

  1. Use the correct HCPCS code for the level of service provided.

  2. Include both origin and destination modifiers (e.g., RH, HR).

  3. Verify mileage accuracy and ensure documentation supports the loaded miles billed.

  4. Check payer-specific guidelines, especially for Medicare vs. commercial insurers.

  5. Watch for frequency limitations and rules about repetitive non-emergency transport (e.g., dialysis patients).

  6. Stay current with annual updates, such as CMS fee schedules and coverage changes.

Recent Changes to Note

In 2025, Medicare introduced updates to ALS2 criteria, emphasizing accurate reporting of advanced interventions. Coders should verify if their state has additional requirements or uses different definitions for emergency vs. non-emergency transport.

Ambulance coding requires attention to detail and a strong understanding of both clinical documentation and billing regulations. With proper training and up-to-date resources, medical coders can ensure claims are compliant and maximize reimbursement for emergency medical services.

NACC https://www.ambulancecompliance.com/

Advanced Life Support Level 2 (ALS2) 2025 Updates https://codingclarified.com/als2-2025-updates/

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