8-Minute Rule Calculator for Therapy Billing (2026)

The 8-minute rule is how Medicare converts treatment time into billable 15-minute units for timed therapy codes. Add up every timed minute in the visit, then bill 1 unit for 8–22 minutes, 2 units for 23–37, 3 units for 38–52, and one more unit for each additional 15 minutes. That total is the ceiling for the day; you then spread those units across codes by the time spent on each.

Enter each timed code and its minutes below. The calculator applies the counting method in the Medicare Claims Processing Manual, shows which code earns the extra unit, compares it with the per-code method many commercial payers use, and prices the visit after the therapy multiple procedure payment reduction.

8-minute rule chart

CMS publishes the time ranges in Pub. 100-04, Chapter 5, §20.2. The pattern continues past two hours: every 15 minutes adds a unit.

How the 8-minute rule works

The manual's rule has two parts: the total minutes cap the units, and each code's own time decides where the units go.

1. Separate timed from untimed codes. Only codes billed in 15-minute increments count toward the total. Untimed services, such as a PT evaluation (97161) or group therapy (97150), are billed as 1 unit regardless of length.
2. Add the timed minutes. Count direct, one-on-one treatment time for every timed code delivered that calendar day.
3. Look up the total in the chart. That number is the most timed units you can bill for the visit.
4. Give each code its full 15-minute units. A code done for 30 minutes gets 2 units before anything else is assigned.
5. Assign the remaining unit by leftover time. Compare each code's leftover minutes (the time beyond its full units) and give the extra unit to the largest. If two are tied, either code may take it, but not both.

The manual also says what not to do: "It is not appropriate to count all minutes of treatment in a day toward the units for one code if other services were performed for more than 15 minutes." Billing all units under your highest-paying code is the classic audit finding. CMS's own first two examples split time between neuromuscular re-education and therapeutic exercise; 97110 vs 97112 walks through them.

Worked examples from the CMS manual

Each of these comes straight from the examples in Chapter 5, §20.2. Drag the minutes to see how the units shift.

33 minutes of therapeutic exercise and 7 minutes of manual therapy. 40 total minutes is 3 units. Exercise takes 2 full units (30 minutes) with 3 minutes left over; manual therapy has 7. The third unit goes to 97140, so bill 2 units of 97110 and 1 of 97140.

Four short services totaling 49 minutes. 18 minutes of exercise, 13 of manual therapy, 10 of gait training and 8 of ultrasound add up to 49 minutes, which is 3 units. Bill one unit each for the three longest services (97110, 97140, 97116). The ultrasound (97035) is still documented but not billed, because you can't bill 4 units for under 53 minutes.

Three services of 7 minutes each. 21 total minutes is 1 unit. No service reached 8 minutes on its own, but the total did, so you bill one unit of whichever code is most appropriate.

Medicare 8-minute rule vs the per-code method

CPT's general time convention treats a unit of a timed code as earned once you pass its midpoint, and it is often applied code by code: 8 minutes of any code is 1 unit of that code, no matter what else happened in the visit. Commercial plans and some Medicaid programs follow that approach, sometimes called the "rule of eights" or substantial portion method.

Medicare's method pools the minutes first, so the two methods only agree when every code's leftover time happens to line up. Run the CMS manual's own examples through both:

Neither method always pays more. The per-code count overbills Medicare when leftover minutes on two codes each pass 8, and underbills when several short services add up to a unit no single one earns. Check each payer's therapy reimbursement policy and bill the method it names; the calculator shows both.

Who the 8-minute rule applies to

The counting rules apply to outpatient physical therapy, occupational therapy and speech-language pathology services billed to Medicare Part B with timed codes, whether billed on a professional claim (CMS-1500 or 837P) or an institutional claim (CMS-1450 or 837I). That covers private practices, outpatient hospital departments, rehab agencies, CORFs and skilled nursing facilities billing Part B. Physicians and nonphysician practitioners who bill "always therapy" codes follow the same therapy policies.

Medicare Advantage plans and Medicaid programs set their own billing policies. Many mirror Medicare; some don't. "Medicaid 8-minute rule" questions have state-by-state answers, so check your state's therapy billing manual.

What the units are worth

Units are only half the claim. Medicare then applies the therapy multiple procedure payment reduction: the unit with the highest practice expense is paid in full, and every other therapy unit that day has its practice expense cut by 50%. The calculator above applies it automatically; here is one visit priced line by line.

Three other Medicare rules change what a unit pays:

• Therapy modifiers. Every "always therapy" code needs GP, GO or GN to show which plan of care it belongs to. Claims without one are returned.
• Therapy assistants. Services furnished in whole or in part by a PTA or OTA carry CQ or CO. Medicare cuts its payment by 15% after coinsurance; the allowed amount is unchanged (CMS, Therapy Services; Transmittal R11129CP).
• KX threshold. For 2026, CMS set the KX modifier threshold at $2,480 for PT and SLP combined and $2,480 for OT. Above it, add the KX modifier to attest the care is medically necessary.

For a single code's local rate, use the rate card: 97110 is the most-billed timed therapy code.