When someone mentions the words “physical therapy billing,” terms like “easy” or “simple” probably don’t leap to mind. After all, every payer has its own way of doing things, and the rules are rarely straightforward—especially when you start throwing in other terms like “8-minute rule” or “mixed remainders.” For that reason, we thought we’d take you through a few unique physical therapy billing scenarios—some of which are based on the examples included in this resource from the APTA and this resource from compliance expert Rick Gawenda, PT—and talk about how many units to bill for them (and why): 

Note: For the following scenarios, we will assume each patient is a Medicare Part B beneficiary.

Scenario 1: Multiple CPT Code Combinations

A Medicare beneficiary comes to your clinic for treatment following a left cerebral vascular accident three weeks prior. You treat the patient with:

  • 15 minutes of transfer training,
  • 10 minutes of pre-gait activities,
  • 25 minutes of range of motion (ROM) and strengthening exercises, and
  • 10 minutes of balance and postural exercises.

The CPT Codes

Per the Medicare 8-minute rule, it would be appropriate to bill Medicare in one of these three ways:

  1. two units of 97110 (therapeutic exercise), one unit of 97112 (neuromuscular reeducation), and one unit of 97116 (gait training)
  2. two units of 97110 and two units of 97116
  3. one unit of 97110, one unit of 97112, and two units of 97116

The Rationale

For this patient, the total treatment time for all timed CPT codes is 60 minutes. Per the chart below (i.e., the Medicare 8-Minute Rule chart), that means you can bill four 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

During this treatment session, you provided the patient with 15 minutes of transfer training and 10 minutes of pre-gait activities, which gives you a total of 25 minutes of gait-focused treatment. Additionally, you spent 25 minutes working with the patient on strengthening and ROM exercises as well as 10 minutes on sitting balance. Because some of these exercises could be covered by more than one of the aforementioned codes, you could bill any one of the three code combinations listed above. Just be sure to support your choice with your documentation.

Scenario 2: Whirlpool and Wound Care

A Medicare beneficiary comes to you for treatment of an open wound due to arterial insufficiency. The treatment consists of:

  • a 25-minute, moderate-complexity evaluation,
  • 10 minutes of sharp debridement with a total wound surface of 15 square centimeters,
  • 20 minutes of whirlpool, and
  • 15 minutes of gait training.

The Codes

To correctly bill for this patient, you would use (again, per the 8-minute rule):

  • one unit of 97166 (PT evaluation; moderate complexity),
  • one unit of 97597 (wound care selective; removal of devitalized tissue from wounds less than or equal to 20 square centimeters), and 
  • one unit of 97116 (gait training).

The Rationale

For the above patient, the total treatment time for all timed CPT codes is 15 minutes. Per the chart above, that means you could bill for a single unit of timed CPT codes. The only timed service in this scenario is gait training. Thus, you would apply the one billable unit to CPT code 97116. Because 97001 and 97597 are untimed codes, you would bill one unit for each.

Note: 97597 includes whirlpool charges in the reimbursement, so you would not bill CPT code 97022 (whirlpool).

Scenario 3: Mixed Remainder (Example 1)

You are treating a Medicare beneficiary who underwent a left total knee replacement less than two weeks ago. During treatment, you administered:

  • 15 minutes of warming up on a treadmill,
  • 35 minutes of ROM exercises and left-extremity strengthening, and
  • 20 minutes of balance exercises using equipment.

The Codes

Per Medicare rules, you could bill one of two ways:

  • three units of 97110 (therapeutic exercise) and one unit of 97112 (neuromuscular reeducation), or
  • two units of 97110 and two units of 97112.

The Rationale

For this patient, the total treatment duration for timed CPT codes is 55 minutes. So, you can bill four units of timed CPT codes. You would not bill for the 15 minutes of treadmill time using the timed CPT codes, as this time constitutes non-skilled therapy (i.e., Medicare will not reimburse you for it). Because you spent at least 15 minutes on balance exercises and 30 minutes on strengthening, you’d bill at least one unit of 97112 and two units of 97110. That leaves you with a 5-minute remainder for both 97112 and 97110. You’ll need to decide which code is the most appropriate to bill for those 10 minutes based on the treatment rendered. You’ll also need to document to support that decision.

Scenario 4: Mixed Remainder (Example 2)

You provide a patient with 15 minutes of manual therapy, 8 minutes of ultrasound, 30 minutes of therapeutic exercise, and 30 minutes of unattended e-stim.

The Codes

In this instance, you would bill:

  • two units of 97110 (therapeutic exercise), 
  • one unit of 97140 (manual therapy), 
  • one unit of 97035 (ultrasound), and 
  • one unit of 97014 (electrical stimulation; unattended).

The Rationale

First, you would calculate the total treatment time, which is as follows: 15 min + 8 min + 30 min + 30 min = 83 total minutes

According to the above-referenced chart, you can bill a maximum of 6 units for the 83 minutes of treatment. However, when you add up your time-based modalities (i.e., therapeutic exercise, manual therapy, and ultrasound), it amounts to 53 minutes. Dividing 53 by 15 gives you three with a remainder of eight. That means you can only bill four units of timed codes.

As for the time the patient spent undergoing e-stim treatment, because 97014 (e-stim; unattended) is an untimed service, you can only bill one unit for that modality—regardless of how long the service lasted. 

Scenario 5: Multiple Patients, Overlapping Appointments

You are treating two patients with overlapping appointments. The first patient arrives at 10:00 AM and begins thirty minutes of ROM and strengthening exercises. The second patient arrives at 10:15 and starts with 15 minutes on the treadmill to target muscular recruitment and posture with a PTA assisting. At 10:30, you set up the first patient doing unattended e-stim; then, you work with the second patient on gait training. At 10:55, you briefly assess the first patient after the e-stim session is complete, and then the patient leaves the clinic. You return to the second patient and provide gait training. This patient leaves at 11:10 AM.

The Codes

For the first patient, you would bill:

  • two units of 97110 (therapeutic exercise), and
  • one unit of 97014 (electrical stimulation, unattended).

For the second patient, you would bill:

  • two units of 97116 (gait training), and
  • one unit of 97112 (neuromuscular reeducation).

The Rationale

Because you were with the first patient one-on-one from 10:00 AM to 10:30 AM, you would bill two units of 97110. You would also bill one unit of electrical stimulation (97014), as it is an untimed code and a supervised modality.

Because the PTA is providing skilled services under your supervision, you can charge the time the second patient spent with the PTA from 10:15 AM to 10:30 AM as one unit of 97112. Additionally, you can bill two or more units of 97116 for the time spent with you (the PT) from 10:30 AM to 11:10 AM, because you were one-on-one with the patient. You would need to bill two units of gait training—as opposed to three—due to the interruptions during this time.

Scenario 6: Multiple Patients, PTA Assisting

A patient arrives at 9:00 AM, and you start the patient out with 30 minutes of therapeutic exercise. Another patient arrives at 9:30 AM, and you provide that patient with an ultrasound. You examine the ultrasound area but direct a PTA to conduct the ultrasound. During this time, you review the first patient’s home exercise program before the patient leaves the clinic at 9:45 AM. At 9:50 AM, the PTA completes the ultrasound for the second patient, and you assess the patient before administering manual therapy. At 10:15 AM, you instruct the PTA to conduct therapeutic exercises with the patient. At 10:30 AM, a third patient arrives, and you provide this patient with 30 minutes of therapeutic exercises and 15 minutes of icing. The second patient leaves at 10:45 AM upon the completion of the therapeutic exercises.

The Codes

For the first patient, you would bill three units of 97110 (therapeutic exercise).

For the second patient, you would bill:

  • one unit of 97035 (ultrasound),
  • two units of 97140 (manual therapy), and
  • two units of 97110 (therapeutic exercise).

For the third patient, you would bill two units of 97110 (therapeutic exercise).

The Rationale

In this scenario, the first patient received three units of 97110 and two units of 97110 from 9:00 AM to 9:30 AM. After you set the second patient up for the ultrasound, you carry on with the first patient’s HEP. You can also bill this time as a one-on-one service (97110).

Because the PTA attends the second patient’s ultrasound (97035), it is a billable service. You then provide manual therapy to the patient from 9:50 AM to 10:15 AM, which equals two units of 97140. You then provided this patient with therapeutic exercise from 10:15 AM to 10:45 AM, which equals two units of 97110.

Finally, the third patient received therapeutic exercise for 30 minutes, which amounts to two units of 97110. You would not bill for the icing time as hot/cold packs (97010) are bundled under Medicare.


So, there you have it: six physical therapy billing scenarios. Have any burning questions about these scenarios—or others you’ve encountered? Let us know in the comment section below!