It depends on what type of therapy and modality you are talking about. Are you billing time based codes? If so there is a rule of 8, you need to consider. When reporting 97100 you can bill for one or more areas (each 15 minutes), in this case multiple units may be reported on a date of service.
The following information came from: Therapy Billing of Time-Based Codes (Medicare article A52758)
The following is a reference list to be used when converting direct time spent with the patient to billable units for all time-based code services:
1 unit > 8 minutes through 22 minutes
2 units > 23 minutes through 37 minutes
3 units > 38 minutes through 52 minutes
4 units > 53 minutes through 67 minutes
5 units > 68 minutes through 82 minutes
6 units > 83 minutes through 97 minutes
7 units > 98 minutes through 112 minutes
• 20 minutes of manual therapy, CPT 97140
• 20 minutes of therapeutic exercises, CPT 97110
Total time of direct treatment is 40 minutes. This allows for billing of 3 units. Since the direct treatment time for each service is the same, bill either code for 2 units and bill the other code for 1 unit. Please note that it would be inappropriate to bill 3 units for either one of the codes. Correct coding would be either:
a. 2 units of CPT 97140 and 1 unit of CPT 97110 or
b. 2 units of CPT 97110 and 1 unit of CPT 97140.
• 35 minutes of manual therapy, CPT 97140
• 7 minutes of ultrasound, CPT 97035
Total time of direct treatment is 42 minutes, which allows for billing of 3 units. The first 30 minutes spent on CPT 97140 is counted as 2 full units (since the work unit for each CPT code is 15 minutes = 1 unit). The remaining time spent on CPT 97140 (5 minutes) is compared to the time spent on CPT 97035 (7 minutes) and the service that took more
time is the service that should receive the remaining unit. Correct coding would be 2 units of CPT 97140 and 1 unit of CPT 97035.
Other codes are only covered one per date of service, for example; mechanical traction, 97012 - Application of a modality to 1 or more areas; traction, mechanical, only 1 unit of CPT code 97012 is generally covered per date of service.
For 97018 - Application of a modality to 1 or more areas; paraffin bath: Only 1 unit of CPT code 97018 is generally covered per date of service.