Billed in minutes, limited by visits
Physical therapy is a rehabilitation discipline rather than a physician specialty, and its billing works differently from most medical practices. Most treatment codes are billed in 15-minute units based on documented time, payers limit visits or require authorization for each episode of care, and Medicare adds its own modifiers, thresholds and plan-of-care rules. The therapist’s daily note — minutes per service, total treatment time and progress — is the basis for every claim.
Evaluations, timed and untimed codes
| Type | Examples | Billed |
|---|---|---|
| Evaluations | 97161, 97162, 97163 (low, moderate, high complexity); 97164 re-evaluation | Once per encounter, by complexity |
| Timed (constant attendance) | 97110 therapeutic exercise, 97112 neuromuscular re-education, 97140 manual therapy, 97530 therapeutic activities, 97116 gait training | In 15-minute units |
| Untimed (supervised) | 97010–97028 modalities, such as unattended electrical stimulation (97014; G0283 for Medicare) | Once per session |
Counting units
For Medicare and payers that follow it, the 8-minute rule applies: total timed minutes for the session determine the number of units (8–22 minutes is one unit, 23–37 is two, and so on), and those units are assigned to the services where the most time was spent. Some commercial payers instead apply the CPT rule that each code needs at least eight minutes on its own. The practice’s billing system has to know which rule each payer uses.
Medicare modifiers and thresholds
- GP on every outpatient physical therapy line, identifying services under a PT plan of care.
- KX once the patient’s annual therapy spending passes the threshold CMS sets each year, attesting that further therapy is medically necessary and documented; claims above a higher amount may be selected for medical review.
- CQ on services furnished in whole or in part by a physical therapist assistant beyond the de minimis share, which Medicare pays at a reduced rate.
- 59 or X modifiers where NCCI pairs such as 97140 and 97530 are performed in separate, documented time intervals.
Plan of care, authorizations and other payers
Medicare requires a plan of care certified by a physician or qualified practitioner, recertified at least every 90 days or when the plan changes, and a progress report at least every 10 treatment days. Even where state law allows direct access, Medicare payment still depends on certification. Commercial plans often cap visits per year, require authorization through utilization-management vendors, and charge a copay per visit. Workers’ compensation and auto claims follow state fee schedules and need the claim and adjuster details. Each therapist must be credentialed with each payer before treating its patients.