The 8-minute rule, explained with worked examples
How Medicare counts units for timed PT and OT codes: the unit table, which code gets the leftover unit, what doesn't count, and how other plans differ.
The 8-minute rule is how Medicare turns minutes into units for therapy codes billed per 15 minutes. You need at least 8 minutes of timed treatment to bill one unit, and you count units from the total timed minutes in the visit, not code by code.
Run your own visits through our 8-minute rule calculator. It shows the units for each code and why the leftover unit went where it did.
The unit table
| Total timed minutes | Units |
|---|---|
| 8 to 22 | 1 |
| 23 to 37 | 2 |
| 38 to 52 | 3 |
| 53 to 67 | 4 |
| 68 to 82 | 5 |
| 83 to 97 | 6 |
Each row adds 15 minutes. Under 8 timed minutes, bill no timed units.
How to split units between codes
- Add up the timed minutes for every timed code in the visit and find the total units in the table.
- Give each code its full 15-minute units. 33 minutes of one code is 2 full units, with 3 minutes left over.
- Assign any remaining unit to the code with the most minutes left over.
Worked examples
33 minutes of therapeutic exercise (97110) and 7 minutes of manual therapy (97140). 40 timed minutes is 3 units. 97110 gets 2 full units with 3 minutes left over. 97140 has 7 minutes left over, more than 3, so it gets the third unit. Bill 97110 x2 and 97140 x1.
24 minutes of neuromuscular reeducation (97112) and 23 minutes of therapeutic exercise (97110). 47 minutes is 3 units. Each code gets 1 full unit, leaving 9 minutes of 97112 and 8 of 97110. The third unit goes to 97112. Bill 97112 x2 and 97110 x1.
7 minutes of 97110 and 7 minutes of 97140. 14 minutes is 1 unit. Neither code reaches 8 minutes alone, but the total does. Bill 1 unit of either code.
20 minutes of 97530 and 6 minutes of 97140. 26 minutes is 2 units. 97530 gets 1 full unit with 5 minutes left over, and 97140 has 6. The second unit goes to 97140. Bill 97530 x1 and 97140 x1.
A 45-minute evaluation (97162) and 20 minutes of 97110. The evaluation is an untimed code, billed once whatever its length, and its minutes don't count toward timed units. 20 timed minutes is 1 unit of 97110.
What doesn't count
- Untimed codes, such as evaluations, re-evaluations and most speech-language pathology treatment codes.
- Time the patient spends unattended, such as a hot pack or exercise they do on their own while you work with someone else.
- Rest breaks and setup the patient isn't actively part of.
- Documentation after the visit.
Commercial plans can count differently
Many commercial plans follow Medicare's method. Some count each code on its own instead: 8 minutes or more of a code bills one unit of that code, without totaling the visit. Under that method, 7 minutes of 97110 plus 7 minutes of 97140 bills nothing, and 33 plus 7 minutes bills 97110 x2 and no 97140.
Check each plan's billing policy and your contract. The calculator has a per-code switch so you can see both counts.
Document minutes, not units
Write the minutes for each timed code and the total timed minutes in the note. Units are a calculation from those numbers, and a reviewer will redo the math.
Billing private-pay patients? Put the units on a superbill with our free superbill generator.
Sources
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