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Physical Therapists’ Guide to the 8-Minute Rule

Comply with Medicare's 8-Minute Rule for every patient every time with WebPT's built-in 8-Minute Rule alerts. See how it integrates with you.

Heidi Jannenga
5 min read
January 11, 2019
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The key feature of the 8-minute rule—and the origin of its namesake—is that a therapist must provide direct treatment for at least eight minutes to receive payment from Medicare for a time-based (or constant attendance) CPT code.

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?

A service-based CPT code denotes a one-time therapy service provided to the patient that is independent of time. 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 or G0283 for Medicare)

In such scenarios, you can only bill the code once, 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.

Learn how to avoid common PT billing mistakes. Watch our 7 Deadly Sins of PT Billing webinar.

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.

Units Time Frame in Minutes
1 unit 8 to 22 minutes
2 units 23 to 37 minutes
3 units 38 to 52 minutes
4 units 53 to 67 minutes
5 units 68 to 82 minutes
6 units 83 to 97 minutes
7 units 98 to 112 minutes
8 units 113 to 127 minutes


Total Direct Minutes: The total time spent on the direct timed code activities.

Total Treatment Minutes: The total time spent treating the patient (total direct minutes plus minutes spent on untimed codes).

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 (TE), 15 minutes of manual therapy (MT), 8 minutes of ultrasound (US), and 15 minutes of electrical stimulation unattended (ESTIM). 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 four billing units.

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

View additional 8-Minute Rule examples in the blog posts, Everything You Need to Know About the 8-Minute Rule or What is the 8-Minute Rule. And if you're looking to test your 8-minute mastery, try these 8-Minute Rule Brain Teasers on for size.

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 five leftover minutes of therapeutic exercise and three leftover minutes of manual therapy. Individually, neither of these remainders meets the eight-minute threshold. When combined, though, they amount to eight 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 and is sometimes referred to as the AMA 8-minute rule—is a slight variant of CMS’s 8-minute rule. This rule strictly adheres to the Substantial Portion Methodology (SPM), where cumulating minutes or remainders is a no-go. 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, and thus, mixed remainders are not allowed. The math must now be applied to each unit separately, and at face value, the rule of eights may appear to restrict billable units, but that’s not always the case.

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. But, if the therapist had treated the patient for 18 minutes of 97110 and 10 minutes of 98116, the Rule of Eights would allow for two units of 97110 with one unit of 98116. With shrewd and legal coding, the Rule of Eights can increase the number of billable units.

(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.)

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 SVP of Revenue Cycle Management, 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 before 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.


The Best Way to Avoid 8-Minute Rule Mistakes

The 8-minute rule has enough tricky scenarios to trip up even the best billing gurus. 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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See WebPT's 8-Minute Rule tool in action.

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