Billing and practice. 8 minute read.
The 8-minute rule in physical therapy billing, with worked examples
The 8-minute rule is how Medicare turns the minutes you spend on timed CPT codes into 15-minute billing units. On its own, a timed service needs at least 8 minutes before it can be billed, and 8 to 22 minutes is 1 unit. When you deliver more than one timed service in a day, you add all the timed minutes together first, and that total sets how many units you can bill.
The rule sits in the Medicare Claims Processing Manual, Chapter 5, section 20.2, which covers outpatient therapy billed under Medicare Part B. The manual itself does not use that name; the American Physical Therapy Association (APTA) notes that the guideline is often referred to as the 8-minute rule. Other payers can work differently, as the section on commercial insurance explains. This guide explains the published rules with invented examples. It is not billing or legal advice, so check the current CMS manual and your payer contracts before you change how you bill.
What is the 8-minute rule in physical therapy?
Several CPT codes used in therapy are defined in 15-minute units of direct, one-on-one time with the patient. The examples in section 20.2 include therapeutic exercise (97110), neuromuscular reeducation (97112), gait training (97116) and manual therapy (97140). For these timed codes, the units you report depend on the minutes you spent.
Untimed codes work differently. If a code is not defined by a specific timeframe, you report 1 unit however long it took. CMS gives a speech-language pathology evaluation as its example, and the unit chart in the same section allows the PT evaluation and re-evaluation codes (97161 to 97164) 1 unit per day.
So the 8-minute rule only touches timed codes. It answers two questions for each visit: how many units the day's timed minutes are worth, and which codes those units go to. The same section covers occupational therapy and speech-language pathology as well as physical therapy.
The 8-minute rule chart: minutes to units
This is the table CMS publishes in section 20.2.
| Units | Total timed minutes |
|---|---|
| 1 | 8 to 22 |
| 2 | 23 to 37 |
| 3 | 38 to 52 |
| 4 | 53 to 67 |
| 5 | 68 to 82 |
| 6 | 83 to 97 |
| 7 | 98 to 112 |
| 8 | 113 to 127 |
CMS says the pattern stays the same beyond 2 hours, so every further 15 minutes adds a unit. When a single timed service is the only one provided that day, CMS says not to bill it if it lasted under 8 minutes.
The chart is a rounding aid. In CMS's words, it "does not imply that any minute until the eighth should be excluded from the total count." Every minute of direct timed treatment goes into the total.
Total timed minutes versus minutes per code
With more than one timed code in a day, Medicare does not let each code earn its units separately. You add the minutes of all the timed codes, read that total against the chart, and the result caps the timed units for the day. The manual says the total number of timed units that can be billed "is constrained by the total treatment minutes for that day."
Inside that cap, CMS sets two floors. A service performed for at least 15 minutes is billed for at least 1 unit, and one performed for at least 30 minutes for at least 2. CMS also says it is not appropriate to count all of a day's minutes toward one code if other services were performed for more than 15 minutes.
How mixed remainders are assigned
Once you know the total, you share the units out. CMS shows the method in its third example: 33 minutes of therapeutic exercise and 7 minutes of manual therapy, 40 minutes in all, which is 3 units. The first 30 minutes of exercise count as 2 full units. The 3 leftover exercise minutes are then compared with the 7 minutes of manual therapy, and the larger gets the third unit, so the claim shows 2 units of 97110 and 1 unit of 97140.
Written as steps, that method looks like this. The steps are our summary, not CMS wording.
- Add up all timed minutes and read the number of units from the chart.
- Give each code 1 unit for every full 15 minutes it ran.
- Hand out any units still left to the codes with the most leftover minutes, largest first.
Run them on all five of CMS's examples and you get the CMS answer each time. The manual also spells out two special cases. If two or more timed services each ran 7 minutes or less but together reach 8 minutes or more, you bill 1 unit for the service performed for the most minutes. When times are equal, as in CMS's example of 20 minutes each of two codes, you choose which code takes the extra unit.
Which minutes count toward timed codes
Section 20.3 says the clock starts when the therapist, or an assistant under supervision, is directly working with the patient to deliver treatment. The patient should already be in the treatment area and ready to begin. Pre- and post-delivery services are not counted. Time the patient spends resting or going to the toilet is not billed, and neither is time spent waiting for equipment or for other treatment to begin.
Two clinicians on one patient do not double the minutes. CMS uses gait training after a recent stroke as its example, where a therapist and an assistant are both needed in the parallel bars. Each 15 minutes the patient is treated still counts as only 1 unit of 97116.
Does the 8-minute rule apply to commercial insurance?
Not automatically. The 8-minute rule is Medicare's method. APTA describes a second approach, the "passing the midpoint" standard in the time section of the CPT manual (APTA cites the 2021 edition). As APTA describes it, the midpoint of a unit must be passed before that unit can be billed. For a 15-minute code that is 7 minutes and 31 seconds.
APTA notes that the CPT guidelines do not indicate a requirement to add up total minutes to decide how many units to bill. As APTA reads them, a therapist could bill 1 unit each time the midpoint is passed for that code, so each code is judged on its own.
Which method applies depends on the payer. APTA recommends billing consistently to all payers, and it also calls it critical to review payer policy to see whether a payer follows the Medicare 8-minute rule or allows a unit every time the midpoint is passed. If your contract with a payer sets its own threshold, APTA says the contract takes precedence. APTA also recommends that your employer's policy and procedure manual set out how services are coded.
Worked examples
The patients and minutes below are invented to show the arithmetic. They say nothing about which codes suit a real patient; that depends on what you actually did and documented.
Example 1: one timed code
Mr. A has knee osteoarthritis and spends 20 minutes on therapeutic exercise, with nothing else timed that day. 20 minutes falls in the 8 to 22 range, so it is 1 unit of 97110. At 23 minutes it would have been 2 units. Had he managed only 6 minutes, that lone service would fall under 8 minutes and would not be billed under the Medicare rule.
Example 2: two codes with mixed remainders
Ms. B, low back pain:
| Code | Minutes | Full 15-minute units | Leftover minutes |
|---|---|---|---|
| 97110 therapeutic exercise | 28 | 1 | 13 |
| 97140 manual therapy | 12 | 0 | 12 |
| Total | 40 | 1 |
A total of 40 timed minutes is 3 units. Exercise has already taken 1 unit with its full 15 minutes, which leaves 2 to hand out. The two largest leftovers are 13 minutes of exercise and 12 of manual therapy, so each gets one: 2 units of 97110 and 1 unit of 97140.
Example 3: a long code and a short one
Mr. C, recovering from an ankle sprain:
| Code | Minutes | Full 15-minute units | Leftover minutes |
|---|---|---|---|
| 97110 therapeutic exercise | 38 | 2 | 8 |
| 97140 manual therapy | 7 | 0 | 7 |
| Total | 45 | 2 |
A total of 45 minutes is 3 units. The third unit goes to the larger leftover, and 8 minutes of exercise beats 7 of manual therapy. The claim shows 3 units of 97110 and none of 97140.
Compare that with CMS's own 33 and 7 minute example above, where 7 minutes of manual therapy beat 3 leftover minutes of exercise. The manual therapy in Mr. C's visit still goes in the note. CMS says the same about the unbilled ultrasound in its fourth example: you would still document it. The Benefit Policy Manual asks for every timed service to be recorded, billed or not, because unbilled timed services can affect the billing.
Example 4: several short services
Mrs. D, who has balance problems, does 6 minutes of therapeutic exercise, 5 of neuromuscular reeducation and 4 of gait training. That is 15 timed minutes, worth 1 unit. Every service ran 7 minutes or less, so the unit goes to the one performed for the most minutes: 1 unit of 97110.
Example 5: the same visit under two payer policies
Mr. E receives 10 minutes each of therapeutic exercise, neuromuscular reeducation and manual therapy. Under the Medicare rule, 30 total minutes is 2 units. All three leftovers are equal, so you choose which two codes to bill, as CMS does with equal times in its second and fifth examples.
Under a payer that follows the per-code midpoint approach, as APTA describes the CPT standard, each 10-minute service passes 7 minutes and 31 seconds on its own, which would make 3 units. One visit, 2 units for Medicare and 3 for that payer, which is why APTA says to check the payer's policy first.
How to document timed minutes
Section 20.2 points to the Medicare Benefit Policy Manual, Chapter 15, section 220.3 for therapy documentation. Part E of that section lists what each Medicare treatment note must contain. For timed codes, these are the parts that matter:
- The total timed code treatment minutes and the total treatment time in minutes, as two separate numbers. Total treatment time includes timed and untimed codes but not time for services that cannot be billed, such as rest periods.
- Each intervention you provided and billed, timed and untimed, in words that can be compared with the codes on the claim.
- Every service represented by a timed code, whether or not you billed it, like the manual therapy in example 3.
- Billing that is consistent with the total timed minutes.
The same part also sets out what is optional. You may record the minutes for each timed code, but Medicare contractors shall not require it. Recording them shows how the units were shared out across the codes. Details such as repetitions do not need repeating in each note unless they changed from the plan of care. Writing them anyway can help, because "Therapeutic exercise, 12 minutes: sit to stand 3 sets of 10, step-up 2 sets of 8" tells a reader far more than "ther ex 12 min".
For where treatment and dose go in a note, see writing SOAP notes. The home program is part of that record too, and the numbers you send the patient should be the ones you wrote down. Choosing the exercises and the dose is covered in how to write a home exercise program.
PocketPhysio has you set sets, reps and hold time for each exercise, and you can type your own cue next to them. The patient opens the program from a link, an SMS or an email, or in Pocket Physio Care, the patient app. WhatsApp works as well. Every exercise in it has its video and spoken voice guide attached.
Common mistakes with the 8-minute rule
- Giving each code its own 8-minute threshold on a Medicare claim. With more than one timed code, the total minutes set the units.
- Putting every minute on one code when another service ran for more than 15 minutes. CMS says this is not appropriate.
- Counting pre- or post-delivery time, rest or toilet breaks, or time spent waiting for equipment as treatment.
- Counting the same minutes twice because two clinicians were with the patient.
- Billing a lone timed service that lasted under 8 minutes.
- Adding untimed minutes, such as an evaluation, to the timed total. They belong in total treatment time.
- A consistent pattern of billing units that average less than 15 minutes each. CMS expects direct contact time per unit to average 15 minutes and says a consistent practice of billing less than that should be highlighted for review.
- Assuming every payer follows Medicare. Check the payer's policy and your contract.
- Leaving total timed minutes out of the note.
The short version
The 8-minute rule is Medicare's method for converting timed therapy minutes into 15-minute units: 8 to 22 minutes is 1 unit, 23 to 37 is 2, and the pattern continues from there. With several timed codes, add all the timed minutes first. Give each code its full 15-minute units, then hand any units left over to the largest remainders. Untimed codes are billed as 1 unit and stay out of the timed total. Other payers may use the CPT midpoint approach instead, so check each payer's policy, and write the total timed minutes and total treatment time in every note.
References
- Centers for Medicare and Medicaid Services. Medicare Claims Processing Manual (Publication 100-04), Chapter 5: Part B Outpatient Rehabilitation and CORF/OPT Services. Section 20.2, Reporting of Service Units With HCPCS (Revision 3670, effective January 1, 2017), and section 20.3, Determining What Time Counts Towards 15-Minute Timed Codes (Revision 1, October 1, 2003). Accessed September 28, 2026. https://www.cms.gov/Regulations-and-Guidance/Guidance/Manuals/downloads/clm104c05.pdf
- Centers for Medicare and Medicaid Services. Medicare Benefit Policy Manual (Publication 100-02), Chapter 15: Covered Medical and Other Health Services. Section 220.3, Documentation Requirements for Therapy Services, part E, Treatment Note (Revision 255, effective January 1, 2019). Accessed September 28, 2026. https://www.cms.gov/Regulations-and-Guidance/Guidance/Manuals/downloads/bp102c15.pdf
- American Physical Therapy Association. Coding for Timed Codes. Accessed September 28, 2026. https://www.apta.org/your-practice/payment/coding-billing/coding-for-timed-codes
Written and checked by the PocketPhysio editorial team. Last updated 2026-09-28.