Physical Therapy Billing Units A Guide to Maximizing Reimbursements

Yes, if services are distinct. Use modifier -59 and document separate times

45 mins = 3 units (8+8+8=24; remaining 21 mins don’t qualify).

The number of units depends on the payer’s rules and the total time spent on timed services:

• Medicare: Follows the 8-minute rule. For example:
  • 8–22 minutes = 1 unit
  • 23–37 minutes = 2 units
  • 38–52 minutes = 3 units
• BCBS/Private Insurance: May use 15-minute increments or allow rounding (e.g., 37 minutes = 2.46 units → 3 units).
  Example: A 45-minute session = 3 units for Medicare (8+8+8=24 mins; remaining 21 mins unused) or 3 units for private payers (45 ÷ 15 = 3).

The 8-minute rule (for Medicare) and 15-minute increments (for many private insurers) govern PT billing:

• Medicare: 1 unit = at least 8 minutes of a timed service. Total units = total qualifying minutes ÷ 15 (rounded down).
• Documentation: Must include start/stop times and service details (e.g., “97110: 15 mins therapeutic exercise”).
• Modifiers: Use -59 for distinct services (e.g., manual therapy + therapeutic activities).

Units represent time-based increments for billing timed therapy services:

• 1 unit = 15 minutes of a CPT code (e.g., 97110, 97140).
• Medicare Exception: Uses the 8-minute rule (8+ mins = 1 unit).
  Example: 20 minutes of manual therapy (97140) = 1 unit for Medicare (8+ mins) or 1.33 units for private payers (20 ÷ 15).