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Understanding 8-Minute Rule for Therapists

8-Minute Rule

The 8-minute rule is the method of calculating the number of billable units Physical Therapists (PTs) should bill Medicare or Medicaid. The 8-minute rule applies to direct contact therapeutic services in which physical therapy provides one on one services to a patient for at least eight minutes. Each timed code is supposed to represent 15 minutes of treatment. Since not all treatments can be perfectly divided into 15-minute increments, the 8-minute rule exists to determine how many units you should bill for in those cases.

Every federal payer requires billing by the 8-minute rule. There are some cases where an insurance company will accept billing via SPM, or Substantial Portion Methodology, but the 8-minute rule is the standard in physical therapy billing for timed services. A lack of understanding about the 8-minute rule often leads to billing errors which can delay reimbursement, force an audit, and/or lead to underbilling. Because more than one service is often provided in a single physical therapy visit and each service has its own code, it’s imperative that a well-understood and well-managed policy concerning the 8-minute rule is in place. 

The 8-minute rule is used by pediatric therapists, including occupational therapists, physical therapists, and speech therapists. In order to fully understand the 8-Minute Rule, you must first understand what constitutes billable time, specifically the difference between service-based and time-based CPT codes.

Calculating Billable Units

To calculate the number of billable units, the total time for time-based services is added together for a particular date of service. This total time is then divided by 15. The end value is the number of billable units.  

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

Example 1: 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.

Example 2: On a particular date of service, the following occurred: 10 minutes of ultrasound, 15 minutes of manual therapy, and 8 minutes of therapeutic exercises, plus 15 minutes of physical therapy evaluation. 10 min. + 15 min. + 8 min. = 33 min./15 = 2 billable units (time-based). Because the physical therapy evaluation qualifies as service-based, these 15 minutes equate to 1 billable unit i.e., total billable units = 3.

Mixed Remainders

When you divide the total timed minutes by 15 and you get a reminder that includes leftover minutes from more than one service (code) those are mixed remainders. If the total of those remainders equals 8 (or more) then you can bill for an additional unit of the service (code) with the greatest time. For example, if there is a remainder of 4 min. manual therapy, 2 min. ultrasound, and 2 min. therapeutic exercises, then these values may be added together for an additional unit billed to manual therapy (the largest remainder) i.e., 4 min. + 2 min. + 2 min. = 8 min. = 1 billable unit.

Avoid Common Mistakes

  • Service-based time must be counted separately as it can only count for one billable unit, regardless of how much time was spent. It should not be added in with the time-based services.
  • The 8-minute rule doesn’t apply to all payers. Although some private insurance companies have adopted the 8-minute rule, not all of them have. For payers that don’t follow Medicaid’s guidelines, you’ll need to make sure you’re billing according to your agreement with that payer.
  • Private insurance companies generally don’t allow for mixed remainders, so you can only bill if an individual activity totals more than 8 minutes.
  • By calculating the total time for time-based services, you may have a qualifying remainder amount that could equal an additional unit. If codes are assigned beforehand without looking at the total, the additional billable unit could be lost.
  • Don’t omit assessment and management time when counting billable minutes. The following things can be included:
    • 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

For any physical therapist submitting claims to different payers, understanding the 8-minute rule is crucial. Hopefully, this blog will help to clear up any confusion you have about when and how to use the 8-minute rule. If you need any assistance in medical coding and billing for your practice, contact us at


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