By Ahmad Bashir · Updated October 26, 2026
Most physical therapy treatment codes, such as therapeutic exercise (97110), neuromuscular re-education (97112), manual therapy (97140) and therapeutic activities (97530), are billed in 15-minute units. The 8-minute rule is how Medicare decides how many of those units you can bill for a visit.
Timed vs. untimed codes
The rule only applies to timed, one-on-one codes. Service-based codes such as PT evaluations (97161–97163), re-evaluations (97164) and unattended electrical stimulation are billed once per visit however long they take, and their minutes do not count toward timed units.
The unit chart
Add up the total minutes of all timed services in the visit, then use this chart:
- 8 to 22 minutes – 1 unit
- 23 to 37 minutes – 2 units
- 38 to 52 minutes – 3 units
- 53 to 67 minutes – 4 units
- 68 to 82 minutes – 5 units
Under Medicare, fewer than 8 total timed minutes cannot be billed as a timed unit.
Worked examples
Example 1: 33 timed minutes
20 minutes of therapeutic exercise (97110) and 13 minutes of manual therapy (97140) add up to 33 minutes, which is 2 units: one for each code.
Example 2: 40 timed minutes
30 minutes of 97110 and 10 minutes of 97140 add up to 40 minutes, which is 3 units. 97110 gets 2 units because it covers two full 15-minute blocks, and the third unit goes to 97140.
Example 3: a code with under 8 minutes
33 minutes of 97110 and 7 minutes of 97112 add up to 40 minutes, so 3 units can be billed. 97110 gets 2 full units with 3 minutes left over. Those 3 minutes are compared with the 7 minutes of 97112, and the third unit goes to 97112 because it has more remaining minutes.
Medicare vs. commercial payers
The 8-minute rule is a Medicare rule. Many commercial payers follow it, but some count each code separately and only allow a unit when that code alone has at least 8 minutes. Check each payer’s policy before applying the Medicare method.
Common 8-minute rule mistakes
- Counting evaluation or other untimed minutes toward timed units
- Billing a unit for every code with 8 or more minutes instead of working from the total
- Not documenting the minutes for each timed code and the total timed minutes
- Using the Medicare method for a payer that counts units per code
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