Free tool · PT, OT and speech
8-minute rule calculator
Enter the minutes for each timed service. You get the Medicare units for the visit, which code gets each unit, and why. Switch to the rule of eights for commercial payers.
Timed services this visit
How we got there
- Total timed minutes: 40 → up to 3 units
- Full 15-minute blocks: 97110 × 2
- Remaining 1 unit goes to the largest leftover minutes: 97140 (7 min)
97140 has only 7 minutes but receives a unit because its leftover minutes are the largest. This follows the CMS method.
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How the calculator assigns units
It follows the Medicare method in four steps, the same way CMS explains it.
- Add the minutes of every timed service in the visit.
- Turn the total into units: 8 to 22 minutes is 1 unit, 23 to 37 is 2, 38 to 52 is 3, and each further 15 minutes adds one more.
- Give each service one unit for every full 15 minutes it ran.
- Give any units left over to the services with the most remaining minutes.
The full method, with four worked examples and a chart, is in our guide to the Medicare 8-minute rule.
Questions
What is the 8-minute rule?
Medicare bills timed therapy codes in 15-minute units. A unit can be billed once at least 8 minutes of a timed service are provided. When several timed services happen in one visit, Medicare adds all the timed minutes together to set the total number of units.
How many units is 38 minutes?
Three units. Under the Medicare method, 38 to 52 total timed minutes equal 3 units. 23 to 37 minutes equal 2 units, and 8 to 22 minutes equal 1 unit.
Can a service with under 8 minutes get a unit?
Yes, under Medicare it can. If the visit’s total timed minutes support another unit, that unit goes to the service with the most leftover minutes, even if that service alone ran under 8 minutes. CMS shows this with a 33-minute and 7-minute visit billed as 3 units.
What is the difference between the Medicare method and the rule of eights?
Medicare pools timed minutes across all services. The rule of eights, used by many commercial payers, counts each code on its own, so every code needs at least 8 minutes. Four services of 8 minutes each are 2 units under Medicare and 4 under the rule of eights.
Do evaluations count toward timed minutes?
No. Evaluations, re-evaluations, group therapy (97150) and unattended electrical stimulation (G0283) are untimed. They are billed as one unit and their minutes count only toward total treatment time.
What happens when two services have the same leftover minutes?
Either one may take the unit. The calculator flags the tie so you can follow your Medicare Administrative Contractor’s guidance and apply one rule consistently.
This calculator gives information, not billing or legal advice. Payer contracts and your Medicare Administrative Contractor’s guidance can differ. Check claims against your payer’s current rules.