97035 CPT Code: Therapeutic Ultrasound Billing Guide

The 97035 CPT code reports the therapeutic application of ultrasound to one or more areas, billed in 15-minute increments. Unlike the unattended modalities, it is a constant-attendance, timed service — the clinician maintains one-on-one contact throughout — which means the 8-minute rule governs how many units you can bill. Get the minutes and the attendance documentation right and 97035 is straightforward; get them wrong and it is a frequent audit target.

What is the 97035 CPT code? 97035 is the Current Procedural Terminology code for therapeutic ultrasound applied to one or more areas, a constant-attendance modality reported in timed 15-minute units rather than as a single flat charge.

Undeny's Take

97035 trips practices on the difference between a modality you supervise and one you attend. Hot packs and unattended e-stim are flat, single-unit charges; ultrasound is constant attendance, so it follows the timed-code math — and that is where the units go wrong. A six-minute application billed as a unit, or two units claimed for eighteen minutes, are the classic 97035 errors the 8-minute rule catches. Document the actual minutes, the anatomical site, and the device settings, and bill units by the rule, not by habit. The denials here are almost always arithmetic, not clinical.

What 97035 Covers

97035 covers therapeutic ultrasound delivered as a constant-attendance modality: the therapist applies the ultrasound and remains in direct one-on-one contact for the duration, commonly to promote tissue healing, reduce inflammation, or address musculoskeletal pain. Because attendance is constant rather than supervised-at-a-distance, it is a timed service and scales with treatment minutes, unlike the flat unattended modalities billed once per session.

Timed Units and the 8-Minute Rule

97035 is a timed code, so units follow the 8-minute rule: one unit requires at least 8 minutes of direct service, with each additional unit requiring another full block of time. A single 15-minute unit covers roughly 8 to 22 minutes of application; only past 23 minutes does a second unit become billable. Reimbursement follows each payer's fee schedule on the Physician Fee Schedule — check your contracted rate or the CPT estimator for a working figure.

Modifiers and Documentation

• GP — service furnished under an outpatient physical-therapy plan of care.
• 59 / XU — distinct service, when payer policy requires separating ultrasound from another timed treatment in the same visit.
• Notes must record the treated site, ultrasound frequency and intensity settings, and the timed minutes to substantiate the units.

Common 97035 Denials

• Units billed that the documented minutes do not support under the 8-minute rule.
• Billed as a flat, untimed modality rather than in 15-minute timed units.
• Missing plan-of-care modifier (GP) or insufficient documentation of settings and time.
• Bundling edits with another modality or manual therapy without a distinct-service modifier.

Related Modality and Therapy Codes

97035 is the timed cousin of the unattended modalities like 97014 (electrical stimulation), and it is billed in plans of care alongside timed treatment codes such as 97140 (manual therapy) and 97110 (therapeutic exercise). Browse the full set under CPT codes.

Frequently Asked Questions

Is 97035 a timed code?

Yes. 97035 is a constant-attendance modality billed in 15-minute timed units, so the 8-minute rule applies. You need at least 8 minutes of direct application to bill one unit.

How many units of 97035 can I bill?

Units follow the 8-minute rule: 8–22 minutes supports one unit, and a second unit is not billable until you reach 23 minutes. Bill the units your documented treatment time actually supports.

What is the difference between 97035 and 97014?

97035 is constant-attendance therapeutic ultrasound billed in timed units, while 97014 is unattended electrical stimulation billed as a single flat unit. One scales with minutes; the other does not.

What documentation does 97035 require?

Record the anatomical site treated, the ultrasound frequency and intensity settings, and the timed minutes of application. This supports both the medical necessity and the number of timed units billed.

Informational only — not legal, medical, or billing advice. Always verify against current CPT guidance and your payer policy.

Estimate 97035 reimbursement

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