97035 CPT Code: Ultrasound Billing, Units and Documentation

By Awais Afzal, Healthcare Operations & Data Analyst · Published February 24, 2026 · Updated October 14, 2026

The 97035 CPT code reports therapeutic ultrasound and is billed in timed units. Medicare adds all timed minutes for the day, reads the unit chart, and then assigns units to codes. Ultrasound is billable only when the day's total timed minutes support a unit for it, and the note must show the minutes.

Many 97035 denials and write-offs trace back to the same few habits: counting ultrasound minutes alone instead of the day’s total timed minutes, leaving minutes out of the note, and assuming every payer counts time the way Medicare does. This guide is for owners, billers and front-office leads at rehabilitation and physical therapy practices who need to decide how to bill ultrasound and what to check before a claim leaves. It uses the Medicare Claims Processing Manual as its main source. For the full unit math, see our 8-minute rule guide.

What does the 97035 CPT code cover?

The 97035 CPT code reports therapeutic ultrasound, a physical modality in which a clinician applies sound-wave energy to an area of the body as part of a treatment plan. It is one of the services a therapy practice bills in timed units, which is why it behaves differently from an untimed code. CPT is owned by the AMA, so read the exact descriptor and any guidelines in your current CPT book. The summaries here are our own.

Two things matter for billing. First, CMS treats 97035 as a timed code: in the manual’s worked examples it is counted with other timed services such as therapeutic exercise and manual therapy. Second, an untimed code is reported with one unit, so the units field means something different for each kind of code (CMS, Claims Processing Manual, Chapter 5, Section 20.2). A biller who treats every line the same way will miscount.

This post stays on ultrasound. Evaluation codes and the wider PT code set are in our physical therapy evaluation and treatment codes. Laser is a different modality with its own rules, covered in our laser therapy CPT codes guide.

How does Medicare turn ultrasound minutes into units?

Medicare adds up the minutes of all timed codes delivered on one date of service, then reads the total against a fixed chart. The chart caps how many timed units the visit can carry, no matter how many services were performed. Ultrasound competes with every other timed service for those units.

Source: CMS, Medicare Claims Processing Manual, Chapter 5, Section 20.2 (the chart continues in 15-minute steps).

The same section of the manual adds a rule for the short single service: when only one service is provided in a day, providers should not bill for services performed for less than 8 minutes. So 6 minutes of ultrasound as the only timed service gets no unit, while 10 minutes gets one.

The CMS example where ultrasound is not billed

The manual includes an example built around 97035. A patient receives four timed services in one visit. The total is 49 timed minutes, which the chart limits to 3 units. The manual says to bill the services with the most time, so the ultrasound line is not billed. It also says to document the ultrasound in the treatment notes anyway.

Source: CMS, Medicare Claims Processing Manual, Chapter 5, Section 20.2, example with 97035.

This is why a front desk poster that says “8 minutes equals one unit” misleads. Eight minutes of ultrasound earns a unit only when the visit’s total timed minutes leave room for it. The tie-break rules, remainders and further examples are in our 8-minute rule guide and our physical therapy billing units guide.

Do other payers count 97035 time the same way?

Not always. The chart above is Medicare’s method. Commercial plans, Medicaid programs, workers’ compensation carriers and Medicare Advantage plans can set their own counting method in the contract or payer policy, and some count each code on its own. Treat the payer policy and your contract as the deciding documents.

• Keep a one-page payer sheet that states which counting method each major payer uses and where that was confirmed.
• Check whether the payer limits visits, units per day or the combination of modalities with active treatment.
• Ask the payer rep or read the provider manual before assuming a Medicare rule applies to a commercial line.
• Re-check at the start of each year, because payer policies are updated.

If a payer’s policy conflicts with what you have been billing, fix the process first and then ask about past claims. Appeals and corrected claims are easier when the note already shows the minutes.

What should the note say when you bill 97035?

A note that supports 97035 lets a reviewer rebuild the units on the claim from the page. For Medicare, the treatment encounter note should show total timed code treatment minutes and total treatment time, and the billing must be consistent with those minutes (CMS Benefit Policy Manual, Chapter 15, Section 220.3.5). The other elements below are good practice that commercial payers commonly ask for. Confirm each with the payer.

Source: CMS Benefit Policy Manual, Chapter 15, Section 220.3.5 for the minutes elements; the other rows are our illustration of common payer expectations.

Notice what the table does not say. No payer rule here requires one particular ultrasound frequency or intensity. Settings belong in the note because they show what was done and let another clinician repeat it. Medical necessity is a separate question: the plan of care and the diagnosis on the claim should explain why ultrasound was part of treatment. A diagnosis list that does not connect to the treated area invites a medical-necessity denial.

Build the minutes into the template rather than relying on memory. Required fields for minutes per timed code, total timed minutes and total treatment time make the unit math visible at the point of care and stop most unit mismatches before they reach billing.

Which modifiers and Medicare therapy rules apply to 97035?

For Medicare outpatient therapy, the claim must carry a therapy modifier, and for physical therapy that is GP, which CMS describes as services delivered under an outpatient physical therapy plan of care (Claims Processing Manual, Chapter 5, Section 20.1). Other modifiers and thresholds sit on top of it. Check each against the current CMS therapy services page.

• KX threshold: for 2026, CMS lists $2,480 for PT and speech-language pathology combined, and $2,480 for OT. Claims above the amount need the KX modifier, and the record should support it.
• Targeted medical review: CMS lists a $3,000 threshold for PT and SLP combined and for OT, for calendar year 2021 until 2028.
• CQ and CO: CQ marks PT services furnished in whole or in part by a physical therapist assistant. CO is the occupational therapy assistant equivalent. These services are paid at 85 percent of the otherwise applicable amount, and a service where the assistant’s part does not exceed 10 percent falls under a de minimis standard.
• Multiple procedure payment reduction: since April 1, 2013, Medicare pays the therapy service with the highest practice expense at 100 percent and the other therapy services that day at 50 percent of practice expense.

Modifier 59 is a separate matter. It signals a distinct procedural service and is scrutinized because it overrides an edit. Use it only when the note shows the services were separate, and check the current NCCI table for the pair on your claim. Our modifier 59 guide covers when it is appropriate.

Why do 97035 lines get denied, and what can you check first?

Most 97035 problems fall into a few categories you can check before submission: the units do not match the minutes, a required modifier is missing, the payer limits the service, or the diagnosis does not support it. Read the denial reason on the remittance before you decide which one applies.

1. Units against minutes. Does the unit count match the day’s total timed minutes, and is each minute in the note?
2. Modifiers. Is GP present for Medicare physical therapy, and are KX, CQ or CO needed on this line?
3. Payer policy. Does the payer limit ultrasound by visit count, units per day or pairing with other modalities?
4. Edits. Does the code pair on the claim appear in the current NCCI edit table, and if a modifier is used, does the note support it?
5. Diagnosis and plan of care. Does the diagnosis on the claim explain the treated area, and is the plan of care current?

A claim scrubber or a second reader catches several of these. Our clean claims guide explains what a pre-submission check should cover, and our denial management guide explains how to sort denials by root cause so the same one does not repeat.

Should you handle 97035 billing in-house or bring in help?

Keep it in-house if your note template captures minutes per code, your biller knows each payer’s counting method and someone reviews denials weekly. Bring in help when unit errors, modifier misses or payer-specific rules keep repeating and no one has time to trace them. The question is who owns the check, not who submits the claim.

• In-house works when therapy is a small share of claims and one trained biller can keep a payer sheet current.
• A second reader helps when a busy clinic has several providers using different note habits.
• Outsourced billing fits when you want coding checks, claim follow-up and denial work handled as one process. Our medical billing services cover charge entry through payment posting, and our denial management services cover the appeal side.
• Tracking matters either way. A practice management system that tracks claims by stage shows which therapy claims are waiting on a note correction and who owns each one.

Our recommendations

1. Record minutes for every timed code. Add required fields for minutes per timed code, total timed minutes and total treatment time. Without them, no one can tell whether ultrasound earned a unit.
2. Run the unit math on the whole visit. Add up all timed minutes first, read the chart, then assign units. Never compare a single service to the 8-minute mark in isolation.
3. Keep a payer sheet. List each major payer’s counting method, modifier rules and ultrasound limits, with the date you last confirmed them.
4. Check modifiers before submission. For Medicare PT claims, confirm GP, then KX if the patient is over the threshold and CQ if an assistant furnished part of the service.
5. Review 97035 denials monthly. Sort them by cause (minutes, modifier, policy, diagnosis) and fix the template or process that produced them.

Bottom line

The 97035 CPT code is easy to perform and easy to mis-bill. Units come from the day’s total timed minutes, the note has to show those minutes, and every payer’s rules need checking. If you want help checking therapy claims before they go out, see our medical billing services and our denial management services, or try the revenue calculator to estimate what a few unit errors a week could cost.

Frequently asked questions

Is 97035 a timed code?

Yes. CMS counts it with other timed services in its unit examples, and it is billed in units based on treatment minutes rather than as a single flat service. Read the exact CPT descriptor in your current code book, since AMA owns that wording.

Can I bill 97035 for less than 8 minutes?

Under Medicare’s rule, when only one service is provided in a day, services performed for less than 8 minutes should not be billed. Other payers may count differently, so check the payer policy. Document the minutes either way, because the note is what supports the claim if a reviewer asks how you counted. A short service can still matter for the day’s total.

Why was my 97035 line not billable when I performed it?

Medicare caps timed units by the day’s total timed minutes. In CMS’s own example, 8 minutes of ultrasound went unbilled because 49 total minutes allowed 3 units, which went to services with more minutes. The service was still documented.

Does the 8-minute rule apply to every payer?

No. It is Medicare’s method. Commercial plans, Medicaid, workers’ compensation and Medicare Advantage plans can use their own counting rules. Confirm the method in the contract or payer policy and keep it on a payer sheet.

Which modifier does Medicare need on 97035?

For outpatient physical therapy under a plan of care, the claim needs the GP modifier. Depending on the case, KX (above the annual threshold) and CQ (assistant-furnished services) may also apply. Check the current CMS therapy page and your payer’s manual before the claim goes out, since the exact modifier set depends on the payer and the provider type.

What should the daily note include?

At minimum, the area treated, minutes for each timed code, total timed minutes, total treatment time, and the link to the plan of care. Add the settings your protocol records and the patient’s response. Confirm any extra payer requirements, and use one template for every provider so the same fields appear on every ultrasound visit.

Sources

1. Medicare Claims Processing Manual, Chapter 5 (Sections 20.1 and 20.2) — CMS (2026 (accessed 2026-10-14))
2. Therapy services — CMS (2026)
3. Medicare Benefit Policy Manual, Chapter 15 (Section 220.3.5), transmittal R52BP — CMS (hosted on hhs.gov) (older transmittal)