The Medicare 8-minute rule says a timed therapy code billed in 15-minute units needs at least 8 minutes of direct treatment to count as one unit. For multiple timed services on the same day, you add all timed minutes first, then convert the total to units. CMS made no change to the method for 2026; it's defined in the Medicare Claims Processing Manual, Chapter 5, Section 20.2.
Who the rule applies to
The rule governs outpatient physical therapy, occupational therapy, and speech-language pathology billed to Medicare Part B. That includes private practices, hospital outpatient departments, rehab agencies, CORFs, and skilled nursing facilities billing Part B. Many Medicare Advantage plans and some Medicaid programs follow it too; commercial payers often don't.
Timed vs untimed codes
Only timed (constant attendance) codes go into the 8-minute math. Untimed codes are billed once per day, no matter how long they take, and their minutes are not added to the timed total.
Type | Common codes |
|---|---|
Timed (15-minute units) | 97110 therapeutic exercise, 97112 neuromuscular re-education, 97116 gait training, 97140 manual therapy, 97530 therapeutic activities, 97535 self-care training, 97032 attended e-stim, 97035 ultrasound, 97750 physical performance test, 97129/97130 cognitive intervention |
Untimed (once per day) | 97161–97163 PT evaluations, 97165–97167 OT evaluations, 97164/97168 re-evaluations, 97012 mechanical traction, G0283 unattended e-stim, 97150 group therapy, 92507 speech treatment, 92521–92524 speech evaluations |
The 8-minute rule chart
Total timed minutes | Billable units |
|---|---|
0–7 | 0 |
8–22 | 1 |
23–37 | 2 |
38–52 | 3 |
53–67 | 4 |
68–82 | 5 |
83–97 | 6 |
98–112 | 7 |
113–127 | 8 |
The pattern continues: each additional unit needs 15 more minutes.
How to calculate units in three steps
Add the minutes of every timed code delivered that day.
Convert the total to units with the chart.
Assign units: give each code one unit per full 15 minutes, then give any remaining unit to the code with the most leftover minutes.
Six worked examples
Example | Minutes delivered | Total timed | Units allowed | Bill |
|---|---|---|---|---|
1. Single code | 97110: 20 | 20 | 1 | 97110 × 1 |
2. Two codes, uneven | 97112: 24, 97110: 23 | 47 | 3 | 97112 × 2, 97110 × 1 |
3. Competing leftovers | 97110: 33, 97140: 7 | 40 | 3 | 97110 × 2, 97140 × 1 |
4. Three small services | 97112: 7, 97110: 7, 97140: 7 | 21 | 1 | Any one code × 1 |
5. Evaluation plus treatment | 97162: 40 (untimed), 97110: 10 | 10 | 1 | 97162 × 1, 97110 × 1 |
6. Long session | 97110: 38, 97530: 30, 97140: 12 | 80 | 5 | 97110 × 2, 97530 × 2, 97140 × 1 |
Why example 3 works: 30 of the 33 exercise minutes make two full units. The third unit goes to whichever code has more leftover time: 3 minutes of exercise or 7 of manual therapy. Manual therapy wins.
Why example 6 works: 80 minutes allows 5 units. Full 15-minute blocks give 97110 two units (8 left over) and 97530 two units (0 left over). The fifth unit goes to the larger leftover: 97140's 12 minutes beats 97110's 8.
Medicare 8-minute rule vs the Rule of Eights
Many commercial payers follow the AMA's CPT time convention, often called the Rule of Eights or substantial portion methodology. It applies the 8-minute threshold to each code separately instead of pooling minutes.
Session | Medicare (pooled) | Rule of Eights (per code) |
|---|---|---|
7 + 7 + 7 minutes on three codes | 1 unit | 0 units |
10 + 10 + 10 minutes on three codes | 2 units | 3 units |
33 + 7 minutes on two codes | 3 units | 2 units |
The same session can bill differently by payer, so set your EMR's unit logic per payer, not per clinic.
What counts as treatment time
Count only skilled, direct one-on-one time with the patient: the time in which the therapist or assistant is actively delivering the service. Don't count rest breaks, time the patient spends waiting or exercising unsupervised, or documentation done after the patient leaves. Record start and stop times or total minutes for each timed code, plus the total timed minutes for the visit.
Assistants, CQ/CO modifiers, and the 8-minute rule
When a physical or occupational therapy assistant furnishes more than 10% of a service, the line takes the CQ (PTA) or CO (OTA) modifier and Medicare pays it at 85% of the fee schedule. Minutes the therapist and assistant deliver together count as the therapist's. When a final unit could go either way, CMS guidance applies the 8-minute threshold to decide whether it's billed with or without CQ/CO.
KX threshold: the annual check that rides alongside
The 8-minute rule sets units per visit; the KX threshold tracks spending per year. For 2026, CMS set it at $2,480 for PT and SLP combined and $2,480 for OT. Above it, each claim line needs the KX modifier to attest to medical necessity, or Medicare denies it. Targeted medical review can start at $3,000. CMS proposed $2,540 for 2027; confirm the final figure in the CY 2027 fee schedule final rule.
Five mistakes that trigger denials
Applying the 8-minute threshold to each code for Medicare instead of pooling minutes
Adding evaluation or other untimed minutes to the timed total
Billing more units than the total timed minutes support
Giving the leftover unit to the code with fewer remaining minutes
Missing total timed minutes in the daily note
FAQ
What is the Medicare 8-minute rule?
A CMS method requiring at least 8 minutes of a timed service for one 15-minute unit, with minutes from all timed codes pooled before converting to units.
How many units is 38 minutes?
Three units (38–52 minutes).
Does the 8-minute rule apply to evaluations?
No. Evaluations are untimed and billed once regardless of length.
Do private insurers use the 8-minute rule?
Some do; many use the per-code Rule of Eights. Check each payer's policy.
Did the 8-minute rule change in 2026?
No. The methodology is unchanged; the KX threshold rose to $2,480.
Sources: CMS CR 14252 / Transmittal 13437 (2026 KX amounts) · HHS therapy services guidance · Practice Pro 2026 review · WebPT on the 2027 proposed rule
