Billing timed therapy services correctly can make or break a clinic’s revenue, and audits often focus on unit counts. The Medicare 8 minute rule sets how many 15-minute units you can bill based on the minutes of direct treatment you provide.
This guide covers the billing chart, a four-step calculation method, worked examples, and the mistakes that trigger denials.
1. What Is the Medicare 8 Minute Rule?
The Medicare 8 minute rule is a billing guideline used to calculate billable units for timed outpatient therapy services, including physical therapy, occupational therapy, and applicable speech-language pathology services.
Under this rule, most timed therapy CPT codes use 15-minute billing units. At least 8 minutes of direct, one-on-one treatment are required to bill the first unit.
Here’s how it works:
- 8–22 minutes: 1 billable unit
- 23–37 minutes: 2 billable units
- 38–52 minutes: 3 billable units
When multiple timed services are provided, Medicare uses their combined treatment minutes to determine the total allowable units, which must then be assigned to the appropriate CPT codes.
Note: Untimed services, such as therapy evaluations, follow different billing rules.
2. Medicare 8 Minute Rule Billing Chart
This chart shows how the Medicare 8 minute rule converts total timed treatment minutes into billable units. Find the range that includes your total timed minutes for the day, then read across to the number of units.
| Total Timed Minutes | Billable Units |
| 0-7 | 0 |
| 8–22 | 1 |
| 23–37 | 2 |
| 38–52 | 3 |
| 53–67 | 4 |
| 68–82 | 5 |
| 83–97 | 6 |
| 98–112 | 7 |
| 113–127 | 8 |
The pattern continues in 15-minute steps. Each new unit starts once you pass the 8-minute midpoint of the next 15-minute block.
Keep in mind that this chart sets the maximum number of timed units for the visit. Checking each code against the chart separately can lead to billing too many units or too few.
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3. How to Calculate Medicare 8 Minute Rule Units
To calculate Medicare 8 minute rule units, add all qualifying timed therapy minutes, determine the total billable units, and assign them to the appropriate CPT codes. Follow these four steps:
- Step 1: Identify the Timed CPT Codes
List the timed therapy services provided. Exclude untimed services, such as evaluations, from the calculation.
- Step 2: Add Up All Billable Treatment Minutes
Combine all direct, one-on-one treatment minutes for timed services provided on the same date under the same therapy discipline. Exclude waiting time, rest breaks, and nonbillable activities.
- Step 3: Use the 8-Minute Rule Chart
Use the Medicare 8-minute rule chart to convert total timed minutes into billable units:
- 8–22 minutes: 1 unit
- 23–37 minutes: 2 units
- 38–52 minutes: 3 units
- 53–67 minutes: 4 units
- Step 4: Allocate Units to the Correct CPT Codes
Assign one unit for each complete 15-minute block of an individual timed service. Allocate any additional permitted units to services with the most remaining minutes.
Example
If a therapist provides 24 minutes of therapeutic exercise and 23 minutes of neuromuscular reeducation, the combined 47 minutes allow three units: two for therapeutic exercise and one for neuromuscular reeducation.
4. Timed Codes vs. Untimed Codes
Only timed codes fall under the Medicare 8 minute rule. Untimed codes follow their own billing definitions.
| Timed Codes | Untimed (Service-Based) Codes | |
| How they’re billed | In 15-minute units | One unit per session |
| 8-minute rule applies? | Yes | No |
| Minutes count toward the timed total? | Yes | No |
| Examples | 97110, 97112, 97140, 97530 | Evaluations (97161–97163), hot/cold packs (97010), unattended e-stim (97014/G0283) |
Example: A therapist provides 25 minutes of therapeutic exercise (97110) and a 30-minute physical therapy evaluation (97161).
Under Medicare’s billing rules, this supports 2 timed units of 97110 and 1 untimed unit of 97161, assuming the services meet applicable coverage requirements.
The evaluation’s 30 minutes do not count toward the timed-unit calculation.
5. Medicare 8 Minute Rule Examples
These examples show how the calculation works in common situations.
- Example 1: Two timed codes
33 minutes of therapeutic exercise (97110) and 7 minutes of manual therapy (97140) add up to 40 minutes, which allows 3 units. 97110 gets 2 full units (30 minutes), leaving 3 extra minutes. The third unit goes to 97140 because its 7 minutes are more than 97110’s 3 leftover minutes. Bill 97110 × 2 and 97140 × 1.
- Example 2: Small amounts of time on two codes
9 minutes of 97140 and 5 minutes of 97110 add up to 14 minutes, which allows 1 unit. Bill 97140 × 1, since it has more minutes.
- Example 3: Evaluation plus treatment
A 30-minute evaluation (97161) and 20 minutes of 97110 support 1 evaluation unit plus 1 timed unit of 97110.
- Example 4: Short session
6 total timed minutes means no billable timed unit.
6. Which Therapy Services Follow the Medicare 8 Minute Rule?
Common timed codes that follow the Medicare 8 minute rule include:
- 97110: Therapeutic exercises
- 97112: Neuromuscular reeducation
- 97116: Gait training
- 97140: Manual therapy
- 97530: Therapeutic activities
Each of these codes requires direct, one-on-one contact with the patient and is billed in 15-minute units.
Untimed procedures work differently. Therapy evaluations and re-evaluations, supervised modalities, and group therapy are billed per session, so their minutes never count toward the timed total.
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7. Common Billing Mistakes Under the 8 Minute Rule
Most errors under the Medicare 8 minute rule come from mixing up how minutes are counted. Watch for these:
- Applying the rule to each code separately: This method, known as the AMA “Rule of Eights,” is used by some commercial payers. It doesn’t apply to Medicare claims.
- Adding untimed minutes to the timed total: This inflates unit counts and can lead to overpayment findings.
- Counting non-treatment time: Setup, waiting, and rest periods don’t count.
- Billing more units than the total allows: Even if four codes each reach 8 minutes, the total minutes still cap the units.
- Poor documentation: Record both total timed minutes and total treatment time for each visit.
8. FAQs
Does the 8 minute rule apply to Medicare Advantage plans?
Not automatically. Many Medicare Advantage plans follow the Medicare 8 minute rule, but each plan sets its own billing policies. Check your payer contract.
Can a patient be billed for a unit if the session was cut short?
Only if total timed minutes reach at least 8. Below that, no timed unit can be billed.
Does the rule apply to telehealth therapy sessions?
Yes. Medicare telehealth flexibilities for PTs, OTs, and SLPs run through December 31, 2027, and timed codes billed via telehealth follow the same unit rules.
How does Medicare treat time spent by a physical therapist assistant?
PTA minutes count toward the timed total. If a PTA provides more than 10% of a service, add the CQ modifier. That service is then paid at 85% of the fee schedule amount.
9. Final Thoughts
The Medicare 8 minute rule comes down to one principle: add up all timed minutes, use the chart to find the maximum units, and then assign units based on minutes per code. Keep untimed services separate, document carefully, and confirm each payer’s rules before billing.
