Understanding the 8 Minute Rule in Therapy Billing
Struggling to make sense of therapy billing can feel more complex than calculating the monetary value of a movie ticket or a pizza. In Medicare, the 8 minute rule therapy changes how units, services, and payments are handled. Introduced in 1999, the 8 Minute Rule the Rule of Eights ensures fair, accurate reimbursement by assigning one unit for every eight minutes of direct, one-on one treatment. This approach, followed by insurance providers that adopt Medicare standards, helps regulate therapy sessions under time-based CPT (current procedural terminology) codes. In contrast, service-based (untimed) codes depend only on whether the service was provided and documented. Mastering this rule requires clear understanding, detailed documentation, and precise calculation of therapy minutes while managing mixed remainders to ensure nothing slips through. For practitioners in allied health, knowing how to handle this billing system protects the bottom line, avoids costly mistakes, and ensures they get paid what they truly deserve, keeping transactions clean, guidelines followed, and compliance in check. In simple terms, the 8-minute rule explains how total direct treatment time converts into billable units, helping therapists apply the rule confidently during everyday therapy billing.
BLOG OUTLINE
- What Is Meant By the 8-minute rule Therapy
- Time-Based vs. Service-Based CPT Codes
- Quick Reference: 8-Minute Rule Billing Chart
- Example of Application in Billing Situations
- Optimizing Billable Units Through Smart Coding
- Does this Rule Apply to Occupational, Speech, or Mental Health Therapy?
- Step-by-Step Billing Workflow Using the Rule of 8
- Comparing 8-Minute Rule vs. Substantial Portion Method (SPM)
- Ensuring Compliance with Medicare Billing Guidelines
- 8-Minute Rule Exceptions & Payer Differences
- Top EHR Tools That Support Billing with Rule 8
- How this Rule Affects Reimbursement and Audit Risk
- Conclusion
- FAQs
What Is the 8 Minute Rule in Therapy Billing?
Understanding the 8-minute rule of therapy is essential for offering outpatient care. To receive reimbursement, therapists must deliver one-on-one therapy for at least eight minutes of skilled treatment to bill one unit using time-based CPT codes. For example, 30 minutes of physical exercise can be divided into 2 units, using the standard of 15 minutes per unit. The rule, active since 1999, is a trusted guideline by Medicare and other insurance providers for fair medical billing. Mixing service-based and therapy-based procedures like electrical modalities or re-education, makes documentation and tracking crucial to avoid claims disputes. Whether you’re working on a patient visit with untimed tasks or planning administrative flow, using this tool correctly ensures fair compensation and maintains transparency. Knowing how to determine, record, and bill the exact minutes on the visit date protects your professional integrity and streamlines your billing tasks.
In simple terms, the 8-minute rule provides a clear explanation of how to calculate therapy units under Medicare’s billing guidelines, especially when documenting a mix of time-based and service-based CPT codes.
Time-Based vs. Service-Based (Untimed) CPT Codes
Our medical billing experts understand that the key to accurate physical therapy billing lies in distinguishing between time-based and service-based CPT codes. This distinction between time-based and service-based CPT codes is important because only timed services count toward 8-minute rule unit calculations, while untimed codes follow flat-rate billing regardless of duration.
Time-Based Codes
In physical therapy, time-based CPT codes require you to document the total number of minutes a healthcare professional spends in one-on-one contact with a patient during a treatment session. These services—like therapeutic exercises (97110), manual therapy (97140), or GO515 for cognitive skills development—are billed in 15-minute units, but at least eight minutes must be spent to qualify for one unit. If you provide 23 minutes of combined services, the smart move is to add and bill one unit for every 15 minutes, using the eight minute rule to apply any remainder wisely. You can’t include unattended modalities like a hot or cold pack, or electrical stimulation, even if they take time. This method ensures accurate billing and reflects the real intervention time.
Common Time-Based CPT Codes in Therapy
Here is a list of frequently used time-based therapy CPT codes that follow the 8 min rule:
| CPT Code | Description | Time-Based? | Unit Length |
|---|---|---|---|
CPT 97110 | Therapeutic exercises | Yes | 15 mins |
| CPT 97112 | Neuromuscular re-education | Yes | 15 mins |
| CPT 97113 | Aquatic therapy/exercises | Yes | 15 mins |
| CPT 97116 | Gait training therapy | Yes | 15 mins |
| CPT 97124 | Massage therapy | Yes | 15 mins |
| CPT 97140 | Manual therapy techniques | Yes | 15 mins |
| CPT 97530 | Therapeutic activities | Yes | 15 mins |
| CPT 97535 | Self-care/home management training | Yes | 15 mins |
| CPT 97537 | Community/work reintegration training | Yes | 15 mins |
| CPT 97542 | Wheelchair management | Yes | 15 mins |
| CPT 97750 | Physical performance test/measurement | Yes | 15 mins |
| CPT 97755 | Assistive technology assessment | Yes | 15 mins |
| CPT 97760 | Orthotic management & training | Yes | 15 mins |
| CPT 97761 | Prosthetic training | Yes | 15 mins |
| CPT G0283 | Electrical stimulation (attended) | Yes | 15 mins |
| CPT GO515 | Cognitive skills development (often OT) | Yes | 15 mins |
Note: Each of these requires continuous, skilled interaction with the patient. They are not interchangeable with service-based CPT codes.
CPT Codes That Do Not Follow the Rule of 8
Some CPT codes are service-based, meaning they are not billed based on time. Even if the service takes 5 or 20 minutes, they are billed as one unit only, based on whether the service was delivered.
| CPT Code | Description | Time-Based? |
|---|---|---|
| CPT 97010 | Hot/cold packs (unattended) | No |
| CPT 97012 | Mechanical traction | No |
| CPT 97014 | Unattended electrical stimulation | No |
| CPT 97022 | Whirlpool therapy | No |
| CPT 97026 | Infrared light therapy | No |
| CPT 97028 | Ultraviolet therapy | No |
Billing Tip: Never combine service-based minutes with time-based codes when applying this billing rule. Only timed codes count toward total billable units.
Key Takeaway:
If you are unsure whether a CPT code qualifies under the rule, ask:
Is the service time-dependent?
Is it performed one-on-one with the patient?
Is it skilled and documented in minutes?
If the answer is yes, the rule of 8 billing likely applies.
Service-Based Codes
Unlike time-based codes, service-based procedures are billed as flat fees, regardless of how much time you spend. These typically include tasks where direct individual contact isn’t the focus or doesn’t vary, like applying a hot pack. Even if you spend 14 or 20 minutes doing them, it doesn’t affect the payment or billing slot—just one code is used. As a therapist, you need to learn early to document clearly and avoid mixing service-based and time-based codes without knowing how to divide the activity and handle the remaining minutes correctly. This helps your coding selection stay clean and within therapy standards rule, especially when sessions feel like a blend of services that don’t neatly fit into set units.
Because the 8-minute rule applies only to time-based services, understanding this difference between timed and untimed CPT codes is essential, and our guide on physical therapy CPT codes provides additional clarity on which codes follow unit-based billing.
Quick Reference: 8 Minute Rule Billing Chart
This quick reference also serves as a simple 8 minute rule cheat sheet, giving therapists an easy way to follow the 8-minute rule calculation chart during billing
| Total Therapy Minutes | Units to Bill |
|---|---|
| 8–22 minutes | 1 unit |
| 23–37 minutes | 2 units |
| 38–52 minutes | 3 units |
| 53–67 minutes | 4 units |
| 68–82 minutes | 5 units |
| 83–97 minutes | 6 units |
Examples: How to Apply Rule 8 Min in Billing Situations
One of the most common questions therapists have is how the 8 minute rule applies to CPT 97110, which is why clear, real-world examples are essential for understanding correct unit calculation.
A physical therapist provides the following during one outpatient visit:
- Therapeutic Exercise (97110): 20 minutes
- Neuromuscular Re-education (97112): 15 minutes
- Manual Therapy (97140): 10 minutes
Total Timed Minutes = 45
From the table above, 45 minutes = 3 billable units. The therapist could distribute the units like:
- 97110: 1 unit
- 97112: 1 unit
- 97140: 1 unit
Or, if documentation supports, they could assign 2 units to the longer code (e.g., 97110) and 1 to another, as long as each billed code is supported by ≥8 minutes of documented service.
Optimizing Billable Units Through Smart Coding
This rule plays a crucial role in CPT code billing for therapy, especially when using timed codes that represent 15 minutes per unit. In practice, the total treatment time may not always be divided into perfect blocks—for example, manual therapy provided for 6 minutes or ultrasound for 11. According to Medicare guidelines, to bill for one unit, at least eight minutes must be performed, and if more time is left after dividing by 15, an additional unit may be billed. When only seven or fewer minutes remain, the remainder is dropped. To avoid underreporting, therapists should combine time from multiple services, applying a clear formula to maximize accurate billing and ensure compliance with all rules and thresholds. Many reimbursement issues happen because of common 8-minute rule billing errors, so recognizing these mistakes early helps prevent lost units and unnecessary denials.
Mixed Remainders in Unit Billing
Mixed remainders happen when leftover minutes from more than one service—like manual therapy for 5 minutes and ultrasound for 3—are left after you divide the total timed minutes by 15. If the sum of these minutes is at least eight, Medicare allows you to bill an additional unit, but only for the individual service with the biggest time total. For example, in a 60-minute session, if Service 1 is 15, Service 2 is 3, and Service 3 is 5, the remainder (8) can be combined to meet the rule. The calculation then becomes 23 minutes, giving you 1.5 billable units, which means you bill 2 full units—one for Service 1 and one from the mixed remainders, billed to the service with the highest total. Mixed remainders matter because combining leftover timed minutes is a core part of how the 8-minute rule determines additional billable units. This guideline helps therapists maximize reimbursement by using every minute wisely, staying on top of regulations, and making sure no unit is lost.
Non-Medicare Insurers and the 8 Minute Rule
When dealing with the 8-Minute Rule, it’s essential to understand that some insurers may use different billing methods, like the Substantial Portion Methodology (SPM). Unlike the 8-Minute Rule, which allows you to combine leftover minutes from different services, SPM requires each service to be performed for a substantial portion of the 15 minutes (at least 8 minutes) before billing. For example, if you provide 5 minutes of manual therapy and 3 minutes of ultrasound, under the Rule of 8 Minute, you could combine these leftover minutes to bill an additional unit, but under SPM, no billing occurs unless one service totals at least 8 minutes. To figure out which method to use, always ask the insurance company for their billing guidelines, ensuring you verify whether they prefer the 8 minute Rule or SPM. This proactive approach can help avoid billing issues and ensure you get paid for the services you’ve provided, whether you’re working with Medicare, TRICARE, or any other payer. It’s also worth noting that some non-Medicare insurers follow the same guidelines, while others have their own standards for billing procedures. Always make sure to verify these details upfront to maximize your reimbursement
Does the 8 Minute Rule Apply to OT, SLP, or Mental Health Therapy?
Yes—but with important nuances depending on the therapy type and the payer (Medicare, Medicaid, commercial plans):
🔹 Occupational Therapy (OT)
The OT 8-minute rule does apply to Medicare patients receiving OT services with time-based CPT codes (like 97530 – therapeutic activities). Therapists must track direct contact time and document it clearly.
Example: If you provide 15 minutes of therapeutic exercise (97110) and 10 minutes of self-care training (97535), you can bill two units.
🔹 Speech-Language Pathology (SLP)
For Medicare-covered speech therapy, the 8-minute rule applies to timed services like:
92507 (speech, language, voice therapy, individual)
92508 (group therapy)
Documentation must show face-to-face minutes spent on direct therapy—not prep time.
🔹 Mental Health Therapy
Mental health providers typically do not follow the 8-minute rule. Instead, they use
standard time ranges assigned to CPT codes:
| CPT Code | Description | Time Range |
|---|---|---|
| CPT 90832 | Psychotherapy, 30 minutes | 16–37 minutes |
| CPT 90834 | Psychotherapy, 45 minutes | 38–52 minutes |
| CPT 90837 | Psychotherapy, 60 minutes | 53+ minutes |
Medicare and most payers adhere to these psychotherapy time brackets, not the eight minute rule. However, Modifiers may still apply in mental health billing.
In simple terms, the 8-minute rule works the same way for PT, OT, and SLP time-based codes, as long as the service is skilled, one-on-one, and documented in minutes.
Step-by-Step Billing Workflow
Applying the 8-minute rule correctly requires a structured billing workflow that ensures every minute is accounted for and compliant with payer expectations (especially Medicare). Following a structured, step-by-step workflow provided below makes it easier for providers to apply this rule consistently across different payer requirements:
✅ Step 1: Identify Time-Based CPT Codes
Start by verifying whether the CPT codes used during the session are time-based. Common examples include:
97110 – Therapeutic Exercise
97112 – Neuromuscular Re-education
97530 – Therapeutic Activities
97140 – Manual Therapy
97535 – Self-Care/Home Management Training
Only time-based codes qualify for rule 8 min calculations. Service-based codes (like 97010 – hot/cold packs) are billed once per session regardless of time and are not subject to this rule.
This step-by-step approach acts like a practical 8-minute rule calculation guide, helping therapists translate session minutes into accurate billable units
✅ Step 2: Record Start & End Times Accurately
Document one-on-one direct contact time (not setup, documentation, or rest time). This will serve as proof for time calculation and billing integrity.
Example:
97110: Start 10:00 AM – End 10:20 AM (20 minutes)
97530: Start 10:21 AM – End 10:36 AM (15 minutes)
✅ Step 3: Calculate Total Timed Minutes
Add the time of all billable, timed CPT services for the session. For instance:
97110: 20 minutes
97530: 15 minutes
Total: 35 minutes
✅ Step 4: Determine Billable Units
Use the standard Medicare time-to-unit table:
8–22 mins = 1 unit
23–37 mins = 2 units
38–52 mins = 3 units
and so on…
With 35 total minutes, you can bill 2 units.
✅ Step 5: Assign Units to Procedures
Assign units based on time spent on each code, ensuring each receives at least 8 minutes.
97110 (20 mins) = 1 unit
97530 (15 mins) = 1 unit
✅ Total: 2 Units billed correctly
🛑 Important: Never assign more units than allowed based on total minutes. Overbilling can trigger audits and claim denials.
Comparing 8 Minute Rule vs. Substantial Portion Method (SPM)
Comparing 8 Minute Rule vs. Substantial Portion Method (SPM)In therapy billing, understanding the difference between the 8-minute rule and the Substantial Portion Method (SPM) is crucial. Both methods dictate how time-based services are billed, but they apply to different payer types and follow distinct rules.
🧠 What Is the Substantial Portion Method?
SPM is most common among commercial insurers and differs from the 8-minute rule by requiring each service to independently meet the minimum threshold. The Substantial Portion Method (SPM) is used primarily by commercial (private) insurers, not Medicare. Under SPM:
A unit of service can be billed if the therapist performs more than 50% of the designated time for that CPT code.
For example, a 15-minute timed code (e.g., 97110) only requires 8 minutes or more of service to bill one unit.
🔍 Side-by-Side Comparison Table
Here’s a simplified breakdown of how the two methods differ:
| Feature | 8 Min Rule Medicare | Substantial Portion Method (SPM) |
|---|---|---|
| Used By | Medicare, Medicaid | Most private insurers |
| Calculation | Total timed minutes across all codes | Each code must meet >50% of its unit time |
| Minimum Time to Bill 1 Unit | 8–22 minutes (combined across codes) | 8+ minutes per code individually |
| Applies To | Timed CPT codes only | Timed CPT codes only |
| Common Use Case | Medicare outpatient therapy | Commercial payers (e.g., BCBS, Aetna) |
✅ Example to Clarify:
Case A: 97110 (Therapeutic Exercise)
Time spent: 9 minutes
| Method | Outcome |
|---|---|
| 8-Minute Rule |  Billable (as part of total 1 unit) |
| SPM | Billable (over 50% of 15 mins) |
Case B: 97110 – 7 mins, 97140 – 6 mins, 97530 – 7 mins
Total: 20 minutes
| Method | Outcome |
|---|---|
| 8-Minute Rule | 1 unit (based on total time) |
| SPM |  None (no code met 50% of its own time) |
In practice, the substantial portion method is simply an alternative to the traditional 8 min rule, and understanding this SPM vs 8-minute rule difference helps therapists choose the correct billing approach for each session.
Pro Tip: Always check the payer’s policy to determine use of each. Misapplying one for the other can lead to denials or overpayments.
Ensuring Compliance with Medicare Billing Guidelines
Ensuring compliance with Medicare billing guidelines is crucial for therapists. These expectations form the foundation of Medicare’s 8 min rule guidelines, which place strong emphasis on accurate time tracking and defensible documentation. The use of timed billing codes requires careful documentation of time spent with the patient, ensuring that the services are direct, intense, and one-on-one. Accurate coding and documentation can help approve additional units for billing. A robust compliance program, as advised by the Office of Inspector General (OIG), can help avoid penalties for fraudulent claims. Regular auditing of claims is vital to ensure that billed services match the documentation, and your staff should be well-versed in correct coding practices. Tools like Net Health’s Rehab Therapy Software or Raintree Systems’ ONC-certified EHR system can help reduce friction and human error, streamlining the process to capture more revenue while staying compliant. By staying up-to-date with the latest regulations and conducting regular audits, healthcare providers can ensure their practice runs smoothly and efficiently.
8 Minute Rule Exceptions and Payer Differences
While the 8-Minute Rule is a Medicare standard, not all insurance companies follow the same billing rules. If you’re submitting claims to commercial payers like Aetna, UnitedHealthcare, Cigna, or Blue Cross Blue Shield, it’s critical to verify whether they require time-based billing — and if so, which method they follow.
Do Commercial Payers Follow this eight minute rule?
Not always. Here’s how it breaks down:
| Payer | Follows 8-Minute Rule? | Notes |
|---|---|---|
| Medicare | Yes | Applies to Part B outpatient therapy. Must follow strict 8-minute unit logic. |
| Medicaid |  Varies by state | Some states adopt 8-minute rule; others follow different time thresholds. |
| Aetna | Usually not | Often uses Substantial Portion Method (over 50% of time). |
| Cigna | Often uses SPM | Confirms billable service if 50%+ of time was spent on the service. |
| UnitedHealthcare | Frequently SPM | Time-based but more lenient; may default to 15-minute increments. |
| BCBS (varies by plan) | Mixed | Some plans follow 8-minute rule; others use SPM or proprietary methods. |
| Tricare / VA | Inconsistent | Verify based on regional contractor policies. |
Commercial insurers may follow Medicare’s unit thresholds or apply their own policies, so it’s important for therapists to understand how these commercial insurance 8-minute rule variations work in practice. Our guide on out-of-network billing for California therapists breaks down how private payers set their own requirements, while our overview of insurance plans for mental health providers explains broader differences across major insurers. Medicaid programs also vary by state, and in California, Medi-Cal includes its own documentation expectations for therapy services, which we cover in detail in our guide on Medi-Cal mental health billing.
Pro Tip: Always check the specific provider manual, payer policy, or provider portal for the latest rules. What’s true for Aetna today may not apply next year or in a different state.
Top EHR Tools That Support Rule of 8 Min Billing
Many behavioral health providers also rely on specialty EHR platforms for accurate unit tracking, and our guide on EHR in mental health explains how these systems support billing compliance. Choosing the right EHR platform can make or break your reimbursement process—especially when billing under the 480 seconds billing rule. The following software solutions are trusted in outpatient rehab settings and help automate time tracking, unit calculations, and compliant billing.
1. WebPT
Strengths: Industry leader in physical therapy EHRs, auto-calculates billable units using the 8-minute rule, includes built-in compliance alerts.
Limitations: Pricing is on the higher end; some users note limitations in customization for niche practices.
2. Net Health Therapy (formerly ReDoc)
Strengths: Specially built for Medicare compliance with robust auditing tools and real-time 8-minute rule tracking.
Limitations: User interface may feel dated; requires onboarding to fully utilize advanced features.
3. Raintree Systems
Strengths: Highly customizable workflows and excellent scheduling + billing integrations; supports both 8-minute rule and SPM.
Limitations: Complex setup; requires IT support for advanced customizations.
💡 Why EHR Matters in Rule of 8 Billing
A compliant EHR can automatically:
- Calculate total timed minutes per visit
- Assign correct billing units per CPT code
- Alert for under-documented sessions
- Minimize denials from Medicare and commercial payers
How the 8 Minute Rule Affects Reimbursement and Audit Risk
Mastering the Rule of 8 in billing is not just about getting paid — it’s about protecting your practice from costly audits and compliance issues. Whether you are billing Medicare or private payers, understanding the financial impact and legal implications of time-based services is essential.
💸 Underbilling: Leaving Money on the Table
Failing to round up to the next unit when eligible can lead to significant revenue loss over time.
Therapists may document services but not match those services with appropriate CPT units.
Underbilling reduces overall reimbursement accuracy, impacting cash flow and productivity metrics.
“Underbilling usually happens when leftover minutes are ignored instead of being applied through mixed remainders.”
🚨 Overbilling: A Red Flag for Audits
Billing for more units than justified by documented minutes invites payer scrutiny.
The Office of Inspector General (OIG) routinely investigates overbilling of therapy services.
Medicare Administrative Contractors (MACs) may initiate audits or demand repayments if patterns of overbilling emerge.
“Overbilling under the 8-minute rule often occurs when units are rounded up without meeting the minimum minute requirement.”
📋 Medicare and OIG Focus on Time-Based Services
According to recent OIG work plans, outpatient rehabilitation services — particularly those billed under the 8-Minute Rule — remain a high-priority area for fraud prevention. Proper documentation must support:
Total treatment time for each session
Breakdown of time per CPT code billed
Compliance with Medicare’s unit thresholds
“Providers must ensure the medical necessity and duration of therapy services are clearly documented in alignment with CMS billing guidelines.”
Bottom line: Misapplying the 8-Minute Rule can either cost your practice thousands — or trigger audits that cost even more. Accurate time tracking and defensible documentation are your strongest shields.
Conclusion
Understanding and applying the 8 minute rule in therapy is more than a billing requirement—it’s a framework that protects your practice, ensures fair reimbursement, and keeps your documentation audit-ready. When therapists accurately track direct treatment minutes and follow Medicare’s 8-minute rule billing guidelines, unit calculation becomes clearer and compliance becomes easier to maintain across both time-based and service-based CPT codes. With precise documentation and consistent workflow habits, providers can avoid common errors, strengthen payer confidence, and maximize revenue without fear of denials or recoupments.
Before you go, you may also want to review our guides on physical therapy CPT codes and mental health billing modifiers for deeper insight into payer rules and code-level compliance.
Need Help Navigating the Rule of 8-Min?
Our billing experts at MedStates specialize in Medicare compliance, time-based coding, and denial prevention for outpatient therapy practices.
Contact us for a free consultation or to schedule a billing audit.
