In outpatient physical and occupational therapy, you cannot bill a unit of time-based therapy just because you touched the patient. You must meet the strict mathematical requirements of the Medicare 8-Minute Rule.
The Unit Calculation Chart
To bill time-based codes (97110, 97112, 97140, 97530), you add up the TOTAL one-on-one time spent across all time-based activities, and divide by 15. The remainder must be at least 8 minutes to bill the next unit.
- 1 Unit: 8 to 22 minutes
- 2 Units: 23 to 37 minutes
- 3 Units: 38 to 52 minutes
- 4 Units: 53 to 67 minutes
Untimed Codes
Do NOT include the time spent on untimed codes (like PT Evaluations 97161, or unsupervised modalities like hot/cold packs 97010) in your 8-Minute Rule calculations.
NCCI Edits
Medicare expects your billed units to match the total time logged. If you log 30 minutes of total treatment time but try to bill 3 units (which requires 38 mins), the claim will instantly deny.