Billing for one-on-one therapy and group therapy services can be tricky (so tricky you may need a bit of therapy yourself). You should never use one-on-one CPT codes if you’ve provided group therapy services, as doing so increases your risk of a Medicare audit. But what, exactly, are you allowed to bill? How do you even know if you’ve provided one-on-one or group therapy? Why is Medicare so complicated? While I don’t have the answer to that last question, I can certainly touch on the first two. Let’s begin:

One-on-One Services

One-on-one services—a.k.a. individual therapy—are defined by direct one-on-one patient contact. So, if you bill using one-on-one codes, you’re telling Medicare you definitely had one-on-one contact with that patient. Additionally, as Deb Alexander explained during her presentation at Ascend 2015, one-on-one CPT codes are cumulative, require constant attendance, and are time-based—which means they fall under the 8-Minute Rule. Here’s a breakdown of how many units you can bill based on treatment time:

  • 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

How to Bill for One-on-One Services While Treating Multiple Patients

Even if you’re working with more than one person, it’s possible to bill for one-on-one services. CMS allows direct one-on-one minutes to “occur continuously (15 minutes straight), or in notable episodes (for example, 10 minutes now, 5 minutes later).” However, each individual therapy episode “should be of a sufficient length of time to provide the appropriate skilled treatment in accordance with each patient’s plan of care.” Here’s how CMS explains it:

Let’s say you work with three patients—for the sake of this post, we’ll call them Moe, Larry, and Curly—over one 45-minute period. Each patient receives 8 minutes of direct one-on-one contact with you for the first 24 minutes. Then, you work directly with Moe for an additional 10 minutes, Larry for 5 minutes, and Curly for 6 minutes. So, the total amount of direct one-on-one time for each patient is:

  • Moe: 18 minutes
  • Larry: 13 minutes
  • Curly: 14 minutes

Thus, you’re allowed to bill each stooge—er, patient—for one unit of 97110 (therapeutic exercise).

Group Services

According to CMS, “Group therapy consists of simultaneous treatment to two or more patients who may or may not be doing the same activities. If the therapist is dividing attention among the patients, providing only brief, intermittent personal contact, or giving the same instructions to two or more patients at the same time, it is appropriate to bill each patient one unit of group therapy.” As the APTA explains it, that means the “therapist involved in group therapy services must be in constant attendance, but one-on-one patient contact is not required.”  

Let’s take a look at an example from CMS: You work with two patients—um, we’ll call them Kirk and Spock—over one 25-minute period. Instead of devoting several minutes at a time to each patient, you spend only a minute or two with each one. You continue to trek between them, offering occasional assistance or modifications to both patients, each of whom has a completely different plan of care (gait training and balance work for Kirk and an exercise program for Spock—ya know, so he can live long and prosper). In this case, you’re only allowed to bill each patient for one unit of 97150 (group therapy), given the lack of “continuous or notable, identifiable episodes of direct one-on-one contact with either patient.” Want more group therapy examples? The APTA offers this detailed resource with multiple scenarios for both PTs and PTAs.

One More Thing

In her Ascend 2015 presentation, Deb Alexander also advised that one-on-one codes “should not be billed with another time based procedure or another constant attendance modality for the same 15-minute period.” But, to make matters a bit more complicated, that doesn’t preclude you from billing for both group therapy and individual therapy on the same day—so long as the group session is clearly distinct or independent from the individual services and you use modifier 59. (For more information, check out this modifier 59 post from Brooke Andrus.)


Hopefully, this post answered at least a few of your questions about one-on-one and group therapy services, but as we know, Medicare is complicated, and these are just the basics. For more details, refer to our guides to the 8-Minute Rule, CPT codes, and Medicare. And if you’re new to billing altogether, take a look at my guide to private practice billing.