The key feature of the 8-Minute Rule—and the origin of its namesake—is that to receive payment from Medicare for a time-based (or constant attendance) CPT code, a therapist must provide direct treatment for at least eight minutes.

To correctly apply the 8-Minute Rule, you must first understand the difference between service-based CPT codes and time-based ones.

What are service-based CPT codes?

You would use a service-based (or untimed) code to bill for services such as:

  • physical therapy evaluation (97161, 97162, or 97163) or re-evaluation (97164)
  • hot/cold packs (97010)
  • electrical stimulation (unattended) (97014)

In such scenarios, you can only bill for one code, regardless of how long you spend providing treatment.

What are time-based CPT codes?

Time-based (or constant attendance) codes, on the other hand, allow for variable billing in 15-minute increments. You would use these codes for performing one-on-one services such as:

  • therapeutic exercise (97110)
  • therapeutic activities (97530)
  • manual therapy (97140)
  • neuromuscular re-education (97112)
  • gait training (97116)
  • ultrasound (97035)
  • iontophoresis (97033)
  • electrical stimulation (manual) (97032)

Enter the 8-Minute Rule.

For time-based codes, you must provide direct treatment for at least eight minutes in order to receive reimbursement from Medicare. Basically, when calculating the number of billable units for a particular date of service, Medicare adds up the total minutes of skilled, one-on-one therapy and divides that total by 15. If eight or more minutes are left over, you can bill for one more unit; if seven or fewer minutes remain, you cannot bill an additional unit.


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8-Minute Rule Reference Chart

Below is a quick reference chart. In this chart, the numeric range in the left column represents the total timed minutes, and the sum on the right represents the maximum number of units you can bill according to that time total.

8 - 22 minutes 1 unit
23 - 37 minutes 2 units
38 - 52 minutes 3 units
53 - 67 minutes 4 units
68 - 82 minutes 5 units
83 minutes 6 units

After using the 8-Minute Rule to determine the appropriate number of time-based units for a particular visit, add that total to your number of service-based units. The resulting sum is the total number of units you can bill Medicare for a particular date of service.

8-Minute Rule Example

Let's say that on a single date of service, you perform 30 minutes of therapeutic exercise (EX), 15 minutes of manual therapy (MT), 8 minutes of ultrasound (US), and 15 minutes of electrical stimulation unattended (ESUN). To correctly calculate the charge in accordance with the 8-Minute Rule, you would add the constant attendance procedures and modalities:

30 min + 15 min + 8 min = 53 direct timed minutes, which supports 4 billing units.

The 15 minutes of ESUN supports one additional service-based billing unit for a total of 5 units for this date of service.

View additional 8-Minute Rule examples here and here. If you’re looking to test your 8-minute mastery, try to ace our 8-Minute Rule quiz.

What’s the deal with mixed remainders?

Many times, when you divide the total timed minutes by 15, you get a remainder that includes minutes from more than one service. For example, you might have 5 leftover minutes of therapeutic exercise and 3 leftover minutes of manual therapy. Individually, neither of these remainders meets the 8-minute threshold. When combined, though, they amount to 8 minutes—and per Medicare billing guidelines, that means you can bill one unit of the service with the greatest time total (which, in this case, would be therapeutic exercise).

So what is the Rule of Eights?

The Rule of Eights—which can be found in the CPT code manual—is a slight variant of the 8-Minute Rule. The Rule of Eights still counts billable units in 15-minute increments, but instead of combining the time from multiple units, the rule is applied separately to each unique timed service. Therefore, the math is also applied separately. (Keep in mind that the Rule of Eights only applies to timed codes that have 15 minutes listed as the “usual time” in the operational definition of the code.)

For example, say a therapist bills 10 minutes of 97110 and 10 minutes of 98116 in a single visit. Those codes are considered unique services, and are counted separately. Each service lasted longer than eight minutes, so the therapist can bill for two units total: one unit of 97110 and one unit of 98116.

What about the AMA 8-Minute Rule?

The main difference between Medicare’s 8-Minute Rule and the AMA’s version is how each one handles mixed remainders. Under AMA guidelines, you cannot bill additional units based on the cumulative total of your remainders. In other words, if your leftover minutes result from a combination of services, you cannot bill for any of those remainders unless one of them totals at least eight minutes. So, in the example above, you could not bill for any additional units, because neither the 3 minutes of manual therapy nor the 5 minutes of therapeutic exercise meets the 8-minute minimum.

Does assessment and management time count toward the 8-Minute Rule?

Often, therapists make the mistake of omitting assessment and management time when counting billable minutes. However, according to John Wallace, WebPT’s Chief Business Development Officer of Revenue Cycle Management (RCM), CPT codes actually do make allowances for assessment and management time. That time includes “all the things you have to do to deliver an intervention,” such as:

  • assessing the patient prior to performing a hands-on intervention;
  • assessing the patient’s response to the intervention;
  • instructing, counseling, and advice-giving about at-home self-care;
  • answering patient and/or caregiver questions; and
  • documenting in the presence of the patient.

The key to justifying your decision to bill for assessment and management time lies in your documentation. If the documentation is defensible (i.e., it’s thorough, it accurately describes the treatment, it defends the prescriber’s clinical reasoning, and it’s easily understood by another provider), then payers will likely greenlight the extra minutes.


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What's the best way to avoid 8-Minute Rule mistakes?

The 8-Minute Rule has enough tricky scenarios to trip up even the whizziest math whiz. So, if you want to ensure accurate billing calculations, leave the long division to an EMR with built-in 8-Minute Rule functionality. WebPT automatically double-checks your work for you, alerts you if something doesn’t add up correctly, and lets you know whether you’ve overbilled or underbilled.


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Heidi Jannenga

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