PT billing is detail-heavy — timed vs. untimed codes, the 8-minute rule, Medicare therapy thresholds, and prior auth requirements that vary by payer. One documentation gap or wrong unit count can mean a denied claim or a compliance risk.
Unlike many specialties where you select a single E/M code, PT billing requires correctly distinguishing timed from untimed services, calculating units using the 8-minute rule, applying the right modifiers, and tracking per-patient Medicare therapy thresholds throughout the year. Errors in any of these areas don't just cause denials — they can trigger audits.
Medicare requires that timed PT services be billed in 15-minute units using the 8-minute rule: you must provide at least 8 minutes of a timed service to bill one unit, and the total timed minutes across all services determines the total number of units billed. Most commercial payers follow the same standard.
Underbilling units leaves revenue on the table. Overbilling units — even accidentally — is a compliance risk. We verify unit counts against your documentation before every claim goes out.
Some PT procedures (like hot/cold packs and electrical stimulation) are untimed and billed once per session regardless of duration. Others (like therapeutic exercise and manual therapy) are timed and must be billed in units. Mixing these up is a common and auditable error.
Medicare sets an annual dollar threshold for PT and speech-language pathology combined. Claims above the threshold require the KX modifier, which certifies the service is medically necessary. Missing or misused KX modifiers are among the top reasons PT claims are denied.
Many commercial payers require prior authorization for physical therapy, with visit limits that must be tracked and renewed. Letting authorizations lapse — or billing beyond approved visits — results in non-covered claim denials that are difficult to appeal.
All PT claims must include the GP modifier to indicate services were provided under a physical therapy plan of care. Omitting it is a straightforward denial that's easily preventable with a systematic billing process.
| Code | Service | Notes |
|---|---|---|
| 97010 | Hot or cold packs | Untimed; billed once per session |
| 97012 | Mechanical traction | Untimed; billed once per session |
| 97014 | Electrical stimulation (unattended) | Untimed; billed once per session |
| 97018 | Paraffin bath | Untimed; billed once per session |
| 97035 | Ultrasound | Timed; 15-minute units, 8-minute rule applies |
| 97110 | Therapeutic exercise | Timed; most commonly billed PT code |
| 97112 | Neuromuscular reeducation | Timed; requires specific documentation |
| 97116 | Gait training | Timed; 15-minute units |
| 97140 | Manual therapy | Timed; commonly paired with 97110 |
| 97150 | Therapeutic activities (group) | Untimed; billed per patient in group |
| 97530 | Therapeutic activities (individual) | Timed; functional activity-based treatment |
| 97535 | Self-care/home management training | Timed; HEP instruction, ADL training |
| 97750 | Physical performance test or measurement | Timed; requires written report |
| 97760 | Orthotic management and training | Timed; initial encounter |
Before you can bill insurance, you need to be credentialed with each payer. We handle the full credentialing and recredentialing process for physical therapists in Arizona — including Medicare enrollment, CAQH setup, and commercial payer applications — so your practice can start billing without delays.
Learn about our credentialing services →Whether you’re opening a new PT practice or cleaning up a billing operation that isn’t working, we’re here to help. Reach out for a free, no-pressure consultation.
Request a Free ConsultationLed by Alda Wong, AAPC Certified Professional Coder (CPC) and Certified Professional Biller (CPB) — your billing is in the hands of someone who is actually credentialed to do it right.