Timed vs Untimed CPT Codes in 20 Seconds
- Timed (time-based) CPT codes are billed in 15-minute units of direct, one-on-one care — the more skilled minutes you deliver, the more units you can bill (e.g. 97110, 97112, 97140, 97530).
- Untimed (service-based) CPT codes are billed once per session no matter how long they take — evaluations, hot/cold packs, and group therapy (e.g. 97161–97164, 97010, 97150).
- Only timed codes count toward the Medicare 8-minute rule; untimed codes never enter the timed-minute total.
- To tell them apart, read the CPT descriptor: if it says "each 15 minutes," it's timed; if there's no time unit, it's untimed.
- Getting the timed vs untimed distinction wrong is one of the most common causes of therapy claim denials and audits.
Every clean therapy claim starts with one question: is this CPT code timed or untimed? Get that classification right and your physical therapy billing flows; get it wrong and you either leave money on the table or invite a denial. This guide breaks down timed vs untimed CPT codes for physical therapy, occupational therapy and speech therapy — with code tables, the 8-minute rule connection, modifiers, and the documentation that keeps every unit audit-proof.
Timed vs Untimed CPT Codes at a Glance
Timed CPT codes (also called time-based or direct-contact codes) are billed in 15-minute units based on the one-on-one minutes a therapist spends delivering skilled care, so a single code can be billed multiple times per visit. Untimed CPT codes (also called service-based or session-based codes) are billed once per session regardless of how long the service takes. Only timed codes count toward the Medicare 8-minute rule.
Here is the core difference every PT, OT and SLP biller needs memorized before touching a claim:
| Feature | Timed CPT codes | Untimed CPT codes |
|---|---|---|
| Also called | Time-based / direct-contact | Service-based / session-based |
| How it's billed | In 15-minute units | Once per session |
| Units per visit | Multiple (based on minutes) | One, regardless of time |
| 8-minute rule | Yes — counts toward units | No — excluded from the total |
| Contact required | Constant one-on-one attendance | May be supervised or unattended |
| Examples | 97110, 97112, 97116, 97140, 97530 | 97161–97164, 97010, 97012, 97150 |
Timed · time-based
60 one-on-one minutes of 97110 →
Untimed · service-based
Any length of 97010 (hot pack) →
What Are Timed CPT Codes?
Timed CPT codes are time-based therapy codes billed in 15-minute increments of direct, one-on-one skilled care. To bill one unit, a therapist must provide at least 8 minutes of the service (the 8-minute rule), and additional units require additional 15-minute blocks. Because they reflect hands-on time, timed codes can be billed multiple times per visit and often reimburse more than untimed service-based codes.
Timed codes require the therapist to stay in constant attendance with the patient — these are the active, skilled interventions at the heart of a treatment session. The most commonly billed timed CPT codes across PT and OT include:
| Timed CPT code | Service |
|---|---|
| 97110 | Therapeutic exercise |
| 97112 | Neuromuscular re-education |
| 97116 | Gait training |
| 97140 | Manual therapy |
| 97530 | Therapeutic activities |
| 97535 | Self-care / ADL training |
| 97035 | Ultrasound (constant-attendance modality) |
| 97032 | Electrical stimulation, manual (attended) |
Every one of these timed CPT codes feeds the 8-minute rule chart, which converts total timed minutes into billable therapy units. Miss the minutes in your note and you can't defend the units.
What Are Untimed (Service-Based) CPT Codes?
Untimed CPT codes are service-based codes billed once per session, regardless of how long the service lasts. Whether a hot pack is applied for 5 minutes or 20, or an evaluation takes 30 minutes or an hour, an untimed code is reported as a single unit per date of service. Untimed codes do not count toward the 8-minute rule and can be either supervised or unattended.
A common misconception is that "untimed" means "quick." It doesn't — it means the code isn't measured in time units at all. The most commonly billed untimed CPT codes in therapy include:
| Untimed CPT code | Service |
|---|---|
| 97161 / 97162 / 97163 | Physical therapy evaluation (low/moderate/high complexity) |
| 97164 | Physical therapy re-evaluation |
| 97010 | Hot / cold packs |
| 97012 | Mechanical traction |
| 97014 / G0283 | Electrical stimulation, unattended |
| 97016 | Vasopneumatic device |
| 97150 | Group therapy (two or more patients) |
Billing rule to lock in: an untimed code is billed one unit per session. Billing multiple units of an untimed code — or counting its minutes toward timed units — is a classic red flag that triggers claim denials and audits.
How to Tell If a CPT Code Is Timed or Untimed
To tell if a CPT code is timed or untimed, read its descriptor in the CPT manual. If the description includes a time unit such as "each 15 minutes," the code is timed and billed by the 8-minute rule. If the descriptor has no time reference, the code is untimed and billed once per session. This one-line check settles the timed vs untimed question for almost every therapy CPT code.
- Open the code descriptor. Check the official CPT® wording, not memory — descriptors are updated periodically.
- Look for a time unit. Phrases like "each 15 minutes" or "each 15-minute increment" mean the code is timed.
- No time unit = service-based. If there's no time interval, treat it as untimed and bill one unit per session.
- Confirm the payer. Medicare uses the 8-minute rule; some commercial payers apply the AMA Rule of Eights, which counts differently.
When in doubt, verify the current descriptor and the payer's provider manual — timing status and coverage can change year to year.
Timed vs Untimed CPT Codes for Physical Therapy
In physical therapy, timed CPT codes include 97110, 97112, 97116, 97140, 97530 and 97535, while untimed physical therapy CPT codes include the evaluations 97161–97164 and modalities like 97010 (hot/cold packs) and 97012 (traction). Medicare requires the GP modifier on outpatient physical therapy claims, and only the timed PT codes count toward the 8-minute rule.
Physical therapy is where most billers meet the timed vs untimed distinction first, because a typical PT visit mixes both types. Here's how the common physical therapy CPT codes split:
| Physical therapy CPT code | Service | Timed or untimed? |
|---|---|---|
| 97110 | Therapeutic exercise | Timed |
| 97140 | Manual therapy | Timed |
| 97116 | Gait training | Timed |
| 97161–97163 | PT evaluation | Untimed (one unit) |
| 97164 | PT re-evaluation | Untimed (one unit) |
| 97010 | Hot / cold packs | Untimed |
Accurate physical therapy billing starts with accurate minutes, which is why strong physical therapy documentation with start/stop times protects every timed unit. A purpose-built physical therapy software platform keeps Medicare physical therapy billing clean by linking timed and untimed codes straight to the claim through integrated RCM and billing.
Timed vs Untimed CPT Codes for Occupational Therapy
In occupational therapy, timed CPT codes include 97530 (therapeutic activities), 97535 (self-care/ADL training), 97110 and 97112, while untimed occupational therapy CPT codes include the OT evaluations 97165–97167 and re-evaluation 97168. Medicare requires the GO modifier on outpatient OT claims, and only the timed OT codes count toward the 8-minute rule.
The timed vs untimed logic is identical to PT — only the codes and the therapy modifier change. Common occupational therapy CPT codes divide like this:
| Occupational therapy CPT code | Service | Timed or untimed? |
|---|---|---|
| 97530 | Therapeutic activities | Timed |
| 97535 | Self-care / ADL training | Timed |
| 97110 | Therapeutic exercise | Timed |
| 97165–97167 | OT evaluation | Untimed (one unit) |
| 97168 | OT re-evaluation | Untimed (one unit) |
Clinics running OT documentation and occupational therapy billing on one occupational therapy EMR get these OT billing units calculated for them, with the GO modifier applied automatically — see how clinical documentation feeds Medicare occupational therapy billing without double entry.
Timed vs Untimed CPT Codes for Speech Therapy (SLP)
In speech-language pathology, most core CPT codes are untimed and billed once per session, including 92507 (speech/language treatment), 92526 (dysphagia therapy) and the SLP evaluations 92521–92524. The main timed SLP codes are 97129/97130 (cognitive intervention). Medicare requires the GN modifier on outpatient SLP claims, and only the timed codes count toward the 8-minute rule.
This is the detail that trips up new SLP billers: unlike PT and OT, speech-language pathology billing is mostly service-based. A quick timed vs untimed reference for speech therapy CPT codes:
| Speech therapy CPT code | Service | Timed or untimed? |
|---|---|---|
| 97129 / 97130 | Cognitive intervention | Timed |
| 92607 / 92608 | AAC evaluation | Timed |
| 92507 | Speech / language treatment | Untimed (per session) |
| 92526 | Dysphagia (swallowing) therapy | Untimed (per session) |
| 92521–92524 | SLP evaluations | Untimed |
Whether you handle PT, OT or SLP billing, one connected AI physical therapy software platform keeps timed and untimed codes straight so Medicare speech therapy billing never goes out the wrong way.
Timed vs Untimed and the 8-Minute Rule
The 8-minute rule applies only to timed CPT codes. You add up the total timed, one-on-one minutes in a visit, then convert them to billable units: 8–22 minutes = 1 unit, 23–37 = 2, 38–52 = 3, 53–67 = 4. Untimed CPT codes are billed once per session and are never included in the timed-minute total, even if they take a long time.
This is exactly why the timed vs untimed classification matters so much: if you accidentally count untimed modality minutes (like a 15-minute hot pack) toward your timed total, you inflate your units and expose the claim to an audit. Keep the two buckets separate, run the timed bucket through the rule, and bill each untimed code once.
Go deeper: our 8-minute rule chart and full Medicare 8-minute rule guide show the minute-to-unit math and the largest-remainder method for splitting units across timed codes.
Therapy Modifiers: GP, GO and GN
Medicare requires a therapy discipline modifier on outpatient therapy claims regardless of whether the CPT code is timed or untimed: GP for physical therapy, GO for occupational therapy, and GN for speech-language pathology. These identify the plan of care the service falls under. Additional modifiers like KX (threshold), CQ/CO (assistant-provided) and 59/X-modifiers may also apply.
| Modifier | Meaning | Applies to |
|---|---|---|
| GP | Service under a PT plan of care | Physical therapy |
| GO | Service under an OT plan of care | Occupational therapy |
| GN | Service under an SLP plan of care | Speech-language pathology |
| KX | Medically necessary beyond the therapy threshold | PT / OT / SLP |
| CQ / CO | Service delivered by a PTA / OTA | PT / OT assistants |
Modifier requirements change — confirm current CMS rules and the therapy threshold amount for the year you're billing.
Documentation Requirements for Timed vs Untimed Codes
For timed CPT codes, you must document the total direct treatment minutes (or start/stop times) for each service, excluding rest, setup and untimed modality time. For untimed CPT codes, you don't track minutes, but you must document the clinical rationale and medical necessity. In both cases, the note has to support every unit billed or the unit isn't defensible in an audit.
- Timed codes: record the one-on-one minutes per service so total units are traceable.
- Untimed codes: capture medical necessity and the skilled reason the service was provided.
- Never count setup, rest, or unattended modality time toward timed minutes.
- Keep timed and untimed services clearly separated in the daily note.
Audit-proofing: your therapy documentation must show the timed minutes behind every unit. If the minutes aren't in the note, the unit isn't defensible — one more reason clean documentation and billing compliance go hand in hand.
Timed vs Untimed Mistakes That Trigger Denials
The classification is simple, but these therapy billing mistakes still drive claim denials, downcoding and audits:
- Counting untimed modality minutes (hot packs, unattended e-stim) toward timed units
- Billing more than one unit of an untimed, service-based code
- Billing timed units the documented minutes don't support
- Applying the Medicare 8-minute rule to a commercial payer that uses the Rule of Eights
- Missing start/stop times, leaving timed units undefendable in an audit
- Forgetting the GP, GO or GN therapy modifier on the claim
Stop classifying codes by hand
Let Your EMR Handle Timed vs Untimed Automatically
Practice Pro knows which CPT codes are timed vs untimed and applies the rules for you in real time — it totals timed minutes as clinicians document, converts them to billable units with the 8-minute rule, keeps untimed service-based codes to one unit per session, applies the GP, GO or GN modifier, and flags any unit your note doesn't support, for PT, OT and SLP.
Because Practice Pro connects the clinical note straight to billing and RCM, timed and untimed codes become correct therapy billing units without anyone reaching for a calculator — and claims go out clean the first time. It's built for rehab, not adapted from a generic EHR, and it's one platform for physical therapy, occupational therapy and speech therapy:
Curious how it looks on your workflows? Book a free demo or talk to our team.
Frequently Asked Questions
Sources & References
- Centers for Medicare & Medicaid Services (CMS), Medicare Claims Processing Manual, Chapter 5 — time-based (timed) coding methodology and the 8-minute rule for outpatient therapy.
- American Medical Association (AMA), CPT® Professional Edition — code descriptors classifying services as timed or service-based.
- American Speech-Language-Hearing Association (ASHA) — guidance on timed vs untimed CPT codes for PT, OT and SLP services.
Disclaimer: This guide is provided for educational reference and reflects our understanding of CMS and AMA CPT® guidance as of August 2026. Coding rules, modifiers and payer policies change; always confirm current CPT® descriptors and each payer's provider manual before billing. This is not legal, coding, or reimbursement advice.