How Many Minutes of Therapy Represent One Billing Unit?

In ABA therapy billing, one billing unit represents 15 minutes of service.

Standard Category I CPT codes, such as 97153 (direct therapy), 97155 (protocol modification), and 97156 (family guidance), are all billed in these 15-minute increments. The total number of units reported on an insurance claim reflects the exact duration of care provided during a session.

To ensure accurate billing, providers often follow the 8-minute rule (or mid-session rule) to determine how to round units:

  • At least 8 minutes of a 15-minute block must be completed to count as one unit.
  • For example, a session lasting 23 minutes would be billed as 1 unit, whereas a session lasting 24 minutes would be billed as 2 units.
  • A 53-minute session would be billed as 3 units.

It is important to calculate units separately for each specific CPT code used, as minutes from different codes cannot be combined.


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