Under the Medicare 8-minute rule, you add up all the minutes of timed therapy services given to a patient in one day, then bill one 15-minute unit for each full 15 minutes. If 8 or more minutes are left over, they count as one more unit. Fewer than 8 minutes of a single timed service in a day can't be billed.
The rule decides how many units a PT, OT or speech therapy visit is paid for, so a counting error repeats on every claim. Below are the unit chart, CMS's own examples and the mistakes to check for.
What Is the Medicare 8-Minute Rule?
The Medicare 8-minute rule is how the Centers for Medicare & Medicaid Services counts units for time-based therapy codes. It is set out in the Medicare Claims Processing Manual, Chapter 5, Section 20.2.
It applies mainly to outpatient therapy:
- Physical therapy
- Occupational therapy
- Speech-language pathology
The core idea:
- A provider must spend at least 8 minutes of direct, one-on-one therapy with a patient to bill one unit of a time-based CPT code.
Each unit stands for 15 minutes of treatment, and the units billed rise with the total timed minutes.
How the 8-Minute Rule Works
Time-Based Unit Calculation
The chart in the CMS manual:
Total timed minutes | Units billed |
|---|---|
Less than 8 | 0 (not billable, when only one service is provided that day) |
8 to 22 | 1 |
23 to 37 | 2 |
38 to 52 | 3 |
53 to 67 | 4 |
68 to 82 | 5 |
This pattern continues in 15-minute increments.
Key Principle
To bill an additional unit, the minutes left over after the full 15-minute units must total at least 8.
Example of the 8-Minute Rule
- 20 minutes of timed therapy falls within 8 to 22 minutes: 1 billable unit
- 30 timed minutes falls within 23 to 37 minutes: 2 billable units
What Services Follow the 8-Minute Rule?
The rule applies only to time-based CPT codes, also called constant attendance codes.
Examples of Time-Based Services:
- Therapeutic exercise (97110)
- Manual therapy (97140)
- Neuromuscular re-education (97112)
- Gait training (97116)
These services require direct, one-on-one patient contact to count.
Services That Do NOT Follow the Rule
Some services are untimed or service-based, which means they are billed once regardless of how long they took. Examples:
- Initial evaluations
- Hot or cold packs
- Unattended electrical stimulation
Combining Multiple Services
Most mistakes happen when more than one timed service is given in a session.
Key Rule
- Total time from all time-based services is combined
- Units are calculated from the total time
- The units go to the services that took the most time
- Any service performed for 15 minutes or more gets at least one unit
For example, 10 minutes of therapeutic exercise and 10 minutes of manual therapy total 20 minutes: 1 unit billed. Because both services took the same time, bill one unit of either code. If one service took longer, the unit goes to the service with the greater time.
Worked Examples From the CMS Manual
These come from Section 20.2's own examples:
- 33 minutes of therapeutic exercise (97110) and 7 minutes of manual therapy (97140), 40 minutes in total. 40 minutes is 3 units. Bill 2 units of 97110 and 1 unit of 97140: the first 30 minutes of 97110 make two full units, and the 7 minutes of 97140 beat the 3 minutes of 97110 left over.
- 20 minutes of neuromuscular re-education (97112) and 20 minutes of therapeutic exercise (97110), 40 minutes in total. 3 units. Each service ran at least 15 minutes, so each gets at least one unit. Bill 2 units of either code and 1 of the other, never 3 of one.
- 18 minutes of 97110, 13 minutes of 97140, 10 minutes of gait training (97116) and 8 minutes of ultrasound (97035), 49 minutes in total. Only 3 units, because 49 minutes is below 53. Bill 1 unit each of 97110, 97116 and 97140. The ultrasound isn't billed, but it is still documented.
The last example is the one to remember: the total minutes cap the units, however many services were given.
Who Uses the Medicare 8-Minute Rule?
The Medicare 8-minute rule is used in outpatient settings, including:
- Private therapy practices
- Rehabilitation centers
- Skilled nursing facilities
- Hospital outpatient departments
- Home health services under Medicare Part B
It applies to timed therapy services involving direct, one-on-one patient interaction.
Documentation Requirements
If the note doesn't support the minutes, the units can be taken back on review.
Required Documentation Includes:
- Total timed code treatment minutes
- Total treatment time (timed and untimed minutes)
- Start and end times (good practice, though Medicare does not require the time for each intervention, only the totals)
- Type of therapy performed
- One-on-one interaction confirmation
- Medical necessity
Common Mistakes to Avoid
1. Billing Less Than 8 Minutes
A single timed service under 8 minutes, with nothing else timed that day, can't be billed.
2. Confusing Timed and Untimed Codes
Counting an evaluation's minutes toward timed units overbills.
3. Not Combining Total Time
Counting each service on its own, instead of totaling the minutes, can lose a unit you were entitled to.
4. Poor Documentation
Missing totals or unclear notes can lead to denials and audits.
5. Overestimating Units
Billing a unit for every service performed, when the total minutes don't support that many, is the error in the four-service example above.
6. Leaving Off the Therapy Modifier
Medicare requires the therapy modifier for the plan of care on these codes: GP for physical therapy, GO for occupational therapy, GN for speech-language pathology (same manual, Section 20.2).
Before a claim goes out, check one more thing: whether the payer follows Medicare's method or the Rule of Eights below.
8-Minute Rule vs Rule of Eights
Some providers confuse the Medicare rule with the Rule of Eights.
Medicare 8-Minute Rule
- Combines total time across services
- Based on CMS guidelines
Rule of Eights (AMA)
- Applies time separately to each service
- Does not combine leftover minutes
The Rule of Eights is the common name for CPT's own counting method, and many commercial payers use it. Check each payer's policy: the same visit can bill a different number of units under the two methods. Our post on physical therapy billing mistakes covers this and other common errors.
Where Beeline fits
Beeline bills for physical therapy practices: it counts units from the minutes in your notes, checks the modifiers and payer method before submission, and follows up on what's denied. The physical therapy billing page has a tool to "Count a session's units" from your own minutes. For a second look at your therapy claims, start with a free consultation.
Frequently Asked Questions
What is the 8-minute rule in Medicare?
The 8-minute rule is a billing guideline that allows providers to bill one unit of therapy if at least 8 minutes of service is provided.
How many minutes equal one unit?
A unit stands for 15 minutes; a total of 8 to 22 timed minutes bills one unit.
Can you bill for less than 8 minutes?
No, services under 8 minutes are not billable under Medicare rules when only one service is provided that day.
What is the difference between 8 min rule and rule of eights?
The Medicare rule combines total time, while the rule of eights applies time separately to each service.
Does the 8-minute rule apply to all CPT codes?
No, it only applies to time-based CPT codes, not service-based codes.
What happens if you misuse the 8-minute rule?
Incorrect billing can lead to claim denials, audits, and financial penalties.
Can multiple services be combined?
Yes, total time across services can be combined to calculate billable units.