Why Modifiers Matter in ABA Billing
Modifiers communicate critical information about who provided the service and under what conditions. Many payers require specific modifiers to determine payment — missing or incorrect modifiers are a top cause of ABA claim denials.
Provider Credential Modifiers
| Modifier | Description | Use With |
|---|---|---|
| HO | Master's level education | BCBA (when payer requires it) |
| HN | Bachelor's degree level | BCaBA |
| HM | Less than bachelor's degree | RBT, paraprofessional |
| HP | Doctoral level | PhD-level behavior analyst |
| AH | Clinical psychologist | PhD psychologist rendering ABA |
U-Series Medicaid Modifiers (State-Specific)
U-series modifiers (U1–U9) are state Medicaid-specific and vary significantly. Common uses include:
- U1 — Commonly used for direct therapy (Medicaid)
- U2 — Often used for supervision/oversight codes
- U3–U9 — State-specific designations; verify with your state Medicaid billing manual
Supervision Modifier
GZ — Item or service expected to be denied as not reasonable and necessary (avoid using this inadvertently).
GX — Notice of liability issued, voluntary under payer policy.
Telehealth Modifier
95 — Synchronous telemedicine service rendered via real-time interactive audio and video telecommunications. Required when providing ABA services via telehealth platforms. See our Telehealth Billing guide for details.
Multiple Procedure Modifier
59 — Distinct procedural service. Used when two separate ABA procedures are performed on the same day and need to be billed separately to avoid NCCI bundling edits.
Common Payer-Specific Requirements
- Aetna: Requires HM/HN/HO on 97153/97155 to identify provider credential level
- UHC: Requires credential modifiers; may require GT for telehealth
- Medicaid (most states): U-series modifiers required per state billing manual
- BCBS: Varies by plan — verify with specific plan's ABA policy