Altruis Blog

A session includes 15 minutes of therapeutic exercise, 12 minutes of manual therapy, and 8 minutes of gait training. Thirty-five minutes of skilled, billable time. The question is how many units each code earns, and that is where mixed-code billing under the 8-minute rule tends to go wrong.

The rule is simple with one timed activity. It gets complicated with three or four codes and leftover minutes that do not divide evenly. CMS does not want units calculated code by code in the order a clinician happened to document them. It requires providers to:

• Total the minutes across all timed codes on the visit first
• Calculate total billable units from that combined time
• Assign the units to the codes with the greatest number of billed minutes before assigning any to the codes with less time

A staff member who skips that sequence, and assigns units in documentation order instead, can under-bill or over-bill a session without ever triggering a denial. The claim simply pays for fewer units than the visit earned, and nothing on the remittance flags it.

The root cause is arithmetic. CMS's total-time method has to be applied correctly, every session, for every mixed-code visit on the schedule.

Running a physical therapy (PT) practice often means wearing many hats as clinician, manager, and business owner all at once. When it comes to billing, it's tempting to settle for a service that gets the job done, more or less. Claims go out, some payments come in, and the lights stay on. But "good enough" PT billing services have a way of quietly costing practices far more than they realize, not in one dramatic moment, but in a slow, steady erosion of revenue and time.