The Physical Therapy Billing Cycle
Physical therapy billing is more documentation-intensive than most specialties because of the timed code structure. Every treatment session requires minute-by-minute accounting of services provided, and the total minutes directly determine the number of billable units. A therapist who documents 45 minutes of treatment can bill 3 units. One who documents the same session as 52 minutes can still only bill 3 units. But a therapist who provides 53 minutes of care can bill 4 units. These thresholds make accurate time tracking essential to revenue capture.
Step 1: Authorization and Benefits Verification
Most commercial payers and Medicare Advantage plans require prior authorization for physical therapy. Authorization typically specifies the number of visits approved (commonly 12-20 visits) and the authorization period (60-90 days). Verify authorization status before every visit, not just the first one. Track remaining visits and expiration dates in the practice management system with alerts at 3 visits remaining and 2 weeks before expiration.
For Medicare fee-for-service patients, prior authorization is not required for outpatient PT, but the therapy cap and KX modifier rules apply. Verify the patient current year therapy spending at the start of each episode of care.
Step 2: Treatment Documentation with Time Tracking
Each treatment session must document: the specific interventions performed (therapeutic exercise, manual therapy, etc.), the time spent on each intervention in minutes, the total timed minutes, the total untimed services, patient response to treatment, and progress toward goals. The documentation must support every unit billed.
Use a treatment log format that captures start and stop times for each intervention rather than estimating total minutes after the session. Real-time documentation prevents the common error of underreporting treatment time, which leads to underbilling. A therapist who provides 55 minutes of timed services but estimates “about 45 minutes” loses one billable unit.
Step 3: Unit Calculation and Code Selection
Apply the 8-minute rule to determine billable units. Total all timed minutes across all timed codes, then allocate units to each code proportional to the time spent. If a session includes 20 minutes of 97110 and 20 minutes of 97140 (40 total minutes), you can bill 2 units of 97110 and 1 unit of 97140, or 1 unit of 97110 and 2 units of 97140. The remaining unit goes to the code with the most minutes. Both allocations are valid as long as total units do not exceed what the total minutes support.
Step 4: Claim Submission
PT claims should be submitted within 48 hours of the session. Each claim includes the evaluation or treatment codes, the number of units per timed code, the appropriate modifiers (KX for Medicare cap, GP for PT services under a PT plan of care, 59 for distinct services), and the referring provider NPI when required. The clearinghouse should flag claims where billed units exceed what the documented minutes support.
Step 5: Plan of Care Management
Medicare requires a signed plan of care (POC) from the referring physician for PT services. The POC must be signed before billing the initial evaluation and recertified every 90 days. Claims submitted without a valid, signed POC on file will be denied on audit. Commercial payers have varying POC requirements, but maintaining a signed POC for all patients is a best practice that protects against retroactive denials.
Step 6: Progress Reporting and Re-Authorization
Submit progress reports to referring physicians every 10 visits or 30 days (whichever comes first) for Medicare, or as required by the payer. These reports serve double duty: they fulfill Medicare documentation requirements and support re-authorization requests for commercial payers. Include objective outcome measures (pain scales, range of motion, functional scores) that demonstrate treatment effectiveness.