The 8-Minute & 15-Minute Rule
In order to seek reimbursement for a unit of service for a constant attendance modality or a therapeutic procedure, the provider must spend at least eight minutes (just past the halfway point of 15 minutes) providing that service to the patient. According to CMS (Medicare) guidelines[1], if the service is performed for less than eight minutes, do not bill for the code. The 8-Minute Rule further dictates that in order to bill for additional time-based units, you must spend at least eight minutes providing one-on-one service to the patient to warrant the additional code. For any single timed CPT code on the same day, measured in 15-minute units, providers must bill a single 15-minute unit for treatment greater than or equal to 8 minutes through (and including) 22 minutes. If the duration of any single modality or procedure completed in a day is greater than or equal to 23 minutes (through and including 37 minutes) then 2 units are billed.
Total Billable Units
The units per number of minutes are calculated as follows:
| Units | Time Window |
| 1 | Greater than or equal to 8 minutes through 22 minutes |
| 2 | Greater than or equal to 23 minutes through 37 minutes |
| 3 | Greater than or equal to 38 minutes through 52 minutes |
| 4 | Greater than or equal to 53 minutes through 67 minutes |
If multiple time-based services are performed on the same day in increments of 7 minutes or less and the total time is 8 minutes or greater, bill one unit for the service performed for the most minutes. This is allowed because the total time for all services was greater than the minimum time for one unit.
Note: only direct, one-on-one time with the patient is considered for timed codes.
Another easy calculation for billing multiple timed codes performed during the same visit is:
If 8 minutes or more are leftover, bill one additional unit. If 7 minutes or less are leftover, do not bill an additional unit.
[1] Medicare Claims Processing Manual, 100-4, Chapter 5, Sections 10, 20, 30, 40, 100 Medicare Benefit Policy Manual, 100-2, Chapter 15, sections 220 and 230