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Physical Therapy Billing Services

Physical therapy is billed in units of time, under rules that convert treatment minutes into billable units, require every Medicare line to carry a therapy modifier, and make payment depend on a plan of care that a physician or other practitioner has certified. Small counting errors repeat across every visit in a course of care.

  • Units calculated from timed minutes under each payer's rule
  • GP, CQ and KX modifiers applied where Medicare requires them
  • Plan-of-care certification and progress report dates tracked
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Minutes, units and the plan of care

Most physical therapy treatment codes are timed in 15-minute units. Medicare counts the total minutes of all timed services in a visit and converts them to units, which is known as the 8-minute rule, while other payers may count each code separately. The same visit can produce a different number of billable units depending on the payer.

Medicare also requires a plan of care. The plan must be certified by a physician or non-physician practitioner, generally within 30 days of the initial evaluation, and recertified at least every 90 days, with progress reports at least every 10 treatment days. Missing a certification date can make every visit after it unpayable.

Spending is tracked too. Once a patient's combined physical therapy and speech-language pathology charges for the year pass a threshold that CMS updates every year, claims need the KX modifier to confirm the care is medically necessary, and higher spending can trigger medical review. Because the amount changes annually, we track the current CMS figure instead of quoting one here.

Official source: CMS: Therapy Services (external site)

Therapy codes, units and modifiers

Codes and modifiers physical therapy practices use on almost every claim.

Physical therapy codes and modifiers with billing notes
Codes or modifiersWhat they coverBilling notes
97161 to 97164PT evaluation at low, moderate and high complexity, and re-evaluation.Untimed: one unit per evaluation, with complexity supported by the documentation.
97110, 97112, 97140, 97530Therapeutic exercise, neuromuscular re-education, manual therapy and therapeutic activities.Timed codes billed in 15-minute units. Some timed pairs have NCCI edits that can be bypassed with modifier 59 or XU only when the services are performed in different timed intervals.
GP (and GO, GN)Services delivered under a physical therapy plan of care (occupational therapy and speech-language pathology use GO and GN).Medicare requires the discipline modifier on every therapy line.
KXConfirms medical necessity once the annual therapy threshold is exceeded.CMS updates the threshold every year and we track the current amount; documentation must support continued care.
CQServices furnished in whole or part by a physical therapist assistant.Medicare pays CQ lines at a reduced percentage set in its payment rules; we track the current rate.
97010Hot or cold packs.Bundled by Medicare and not separately paid.

CPT is a registered trademark of the American Medical Association.

Official sources: CMS: Therapy Services (external site), CMS Claims Processing Manual, chapter 5 (outpatient therapy) (external site), CMS Benefit Policy Manual, chapter 15 (plan of care) (external site), CMS NCCI Policy Manual, chapter 11 (physical medicine) (external site), CMS Medicare Coverage Database: article A56566 (outpatient therapy) (external site), CMS: Physician fee schedule relative value file (code descriptors) (external site)

Therapy claim errors that cost the most

  • More units billed than minutes support

    Units counted per code when the payer uses total timed minutes, or the reverse.

  • Plan of care not certified or expired

    Visits after the certification lapsed, or a plan never signed by the referring practitioner.

  • Missing GP modifier

    Medicare therapy lines without a discipline modifier are rejected.

  • KX not added after the threshold

    Claims past the annual threshold without KX are denied even when the care is necessary.

  • PTA services without CQ

    Assistant-delivered minutes billed as if the therapist delivered them.

  • Visit limits or authorizations exhausted

    Commercial plans that cap visits per year or approve a set number of visits at a time.

Our physical therapy billing setup

  1. Step 1: Apply the right counting rule

    Each payer is set to Medicare-style total-minute counting or per-code counting, and units are calculated from the treatment minutes.

  2. Step 2: Watch certification dates

    Plan-of-care certification, recertification and progress report due dates are tracked for each patient.

  3. Step 3: Monitor the annual threshold

    Each Medicare patient's running total is followed, so KX is applied when it is needed and only then.

  4. Step 4: Track visits against approvals

    Visits used are compared with the approval or the annual limit, with renewals requested before they run out.

Medicare's 8-minute rule in practice

Under Medicare, units come from the total minutes of all timed services in the visit.

Total timed minutes and the number of units billable under the Medicare 8-minute rule
Total timed minutesBillable units
8 to 221 unit
23 to 372 units
38 to 523 units
53 to 674 units
68 to 825 units

Fewer than 8 total timed minutes is not billable as a timed unit, and when two short services add up to one unit, it goes to the service with the most minutes. Physical therapy overlaps with chiropractic on manual therapy and exercise codes, but chiropractors bill manipulation codes and have their own Medicare coverage limits.

Frequently asked questions

How does the 8-minute rule work when we use several timed codes?

Add up the minutes of all timed services, convert the total to units, then assign units to the codes in order of minutes spent. A code with only a few minutes may get no unit if the total does not support it.

Do commercial payers follow the 8-minute rule?

Not always. Some payers count each timed code separately instead of totaling the minutes, so the payer contract or policy decides and we set it per payer.

When is the KX modifier needed?

When a Medicare patient's physical therapy and speech-language pathology spending for the year passes the threshold CMS publishes, and the care remains medically necessary and documented. The threshold changes every year, so check the current amount on the CMS therapy page.

Official source: CMS: Therapy Services (external site)

How often does the plan of care need recertifying?

For Medicare, at least every 90 days, or sooner if the plan's duration is shorter or the plan changes significantly.

Can patients see us without a physician referral?

State law decides whether patients can see a therapist without a referral, but payers can still require a referral or certified plan for payment, and Medicare requires plan-of-care certification for payment.

Related services and specialties

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Make sure every therapy minute is billed correctly

A free audit compares billed units with treatment minutes and checks modifiers and certifications across your physical therapy claims.

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