A single day of therapy can contain up to three timed units of service. If a therapy session is properly documented, it is considered to have been performed even if it is not listed on the claim. An improperly coded service can result in an overpayment. The 8 minute rule can help to answer questions such as how many units of a specific therapy service can be billed. There are several other aspects of Medicare therapy billing that must also be addressed in order for a claim to be accurately submitted.
The 8 minute rule states that for each type of therapy performed on the same day, if the total amount of timed units is between 8 and 22, then one unit can be billed. If the total amount of timed units is between 23 and 37, then two units can be billed, and so on. This rule is applied to each type of therapy performed on the same day.
Start with the right scope
The Medicare 8-minute rule states that for therapy services with a code level defining the service as 15 minutes or more, Medicare will only pay for up to 8 minutes of service. The 8 minutes is based on the provider directly and personally providing the therapy service, and cannot be based on the total time of the therapy service.
This rule does not apply to all plans. For example, there are significant differences in other plans such as Medicare Advantage plans, Medicaid, as well as commercial and workers’ compensation plans.
Each discipline has its own rules. For example, the rules state that separate PT and OT minutes cannot be combined. For the same day, two PT or OT sessions cannot be considered the same session.
On the same day, the total number of timed units for all services in each discipline have to be determined first, and then considered for the day’s services.
The Medicare minute-to-unit chart
Use this chart only after you have totaled eligible timed minutes for the same discipline and date of service.
| Total timed minutes | Timed units |
|---|---|
| 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 easy mistake is to think that every 15 minutes automatically creates another unit. It does not. Twenty-two minutes is still one unit. You reach two units at 23 minutes, three at 38, and four at 53.
Calculate the day before assigning codes
The chart gives you the total number of timed units. It does not, by itself, tell you which CPT code gets each unit. Follow this order every time.
1. Separate timed services from untimed services
Timed therapy codes include therapeutic exercises (97110), neuromuscular re-education (97112), gait training (97116), and manual therapy (97140), among others. Just because a code is timed, doesn’t mean you can always bill the full amount documented. For the service to be billable, it must be appropriate and medically necessary.
Untimed therapy codes, including many evaluation and re-evaluation codes, are reporting units based on the description of the code. Services coded this way do not participate in the 8 minute rule.
2. Add only eligible direct, skilled treatment minutes
This includes total timed services for the same discipline provided that day. Do not include rest periods, routine office administration, or unrelated activities.
You must document treatment time as accurately as possible. It is inefficient and fraudulent to round up treatment time to the next 15 minutes, or to report treatment time as 23 minutes when the actual treatment time was 21 minutes.
3. Use the chart to find the day’s timed-unit total
An example, 41 timed minutes is in the range of 38 to 52. The description would support three timed units. At this point, do not determine if these timed units support CPT code 97530, 97110, 97140, or other related codes.
4. Allocate units to the services you performed
Whenever there are multiple codes with time limits, add codes for the total time, and then distribute the whole numbers of codes to the services with the longest time. If a tie occurs, use a method that is defensible, and reference the payer’s policy.
Most inaccuracies in coding occur with time. A code is often given for a service if there is eight minutes of time left after adding up all the time for that code from the previous services, based on the guidance from the Centers for Medicare and Medicaid Services (CMS). CMS mentions that 33 minutes of therapeutic exercise and seven minutes of manual therapy constitute two units of therapeutic exercise and one unit of manual therapy.
Two billing scenarios that show the difference
Mixed services in one treatment period
Suppose a therapist documents:
| Service | Minutes |
|---|---|
| Therapeutic exercise, 97110 | 18 |
| Manual therapy, 97140 | 13 |
| Gait training, 97116 | 10 |
| Therapeutic ultrasound, 97035 | 8 |
| Total timed minutes | 49 |
Forty-nine minutes supports only three timed units. In the CMS example provided, units 97110, 97140 and 97116 are assigned to the services with the longest time documented. Ultrasound time is documented; however, an additional billed unit is not assigned since the total allows only three units.
It is important to understand that the total allowable units is always set and therefore, billed from the bottom up.
This example demonstrates that you cannot always bill the greatest number of codes that fit within the allowable time, as the total allows only three billed units.
Two visits on the same day
Let’s look at a physical therapy billing example. Suppose a physical therapist performs 25 minutes of gait training in the morning. Later in the day, the therapist performs 12 minutes of therapeutic activities and 13 minutes of gait training.
Because the therapy was performed on the same day for the same discipline, the total treatment time for that day is 50 minutes. According to the 8-Minute Rule, this is considered 2 units of gait training for a total of 38 minutes, and 1 unit of therapeutic activities for 12 minutes.
Additionally, if the therapist performs an untimed evaluation on that same day, it may be reported on the same day as the 3 timed units, using the appropriate PT evaluation and/or PT diagnosis code.
Not every therapy code follows this calculation
Do not apply the 8-minute table merely because a code involves therapy or includes a time reference.
- Therapy evaluation and re-evaluation codes are typically untimed and are reported under their own rules.
- Group therapy, such as 97150, is untimed and does not become a timed unit because the group lasted 20 or 40 minutes.
- CPT 96125, standardized cognitive performance testing, is reported per hour and includes qualified professional time for testing, interpretation, and report preparation. It is not a 15-minute 8-minute-rule code.
- Remote therapeutic monitoring has its own setup, device-supply, and 20-minute management rules. Do not run RTM code time through a 15-minute therapy chart.
When in doubt, read the current code descriptor and payer policy before releasing the claim.
CMS and payer rules are not interchangeable
The comparison below keeps the decision practical.
| Billing situation | Safe starting point |
|---|---|
| Medicare Part B outpatient therapy | Use the CMS total-timed-minutes calculation by discipline and date of service. |
| Medicare Advantage | Verify the plan’s provider manual and contract. Do not assume every plan uses the same calculation. |
| Medicaid or managed Medicaid | Check the state or plan manual. Rules can vary. |
| Commercial or other federal payer | Verify the payer’s time methodology. Some use code-by-code or midpoint-style rules instead of Medicare’s total-time method. |
The AMA Rule of Eights can be used for a code-by-code, midpoint calculation. This methodology results in a higher unit value compared to the Medicare method, particularly when multiple services are provided. This should not be construed to mean that you should select the method that results in a higher payment. You must use the method required by the payer that will process your claim.
Documentation that stands up to review
Comprehensive time documentation details the work performed, rationale, and relationship to the care plan.
Your documentation must include:
- Total timed code treatment minutes
- Total treatment minutes
- Services and related CPT codes
- Clinical rationale and documentation of patient’s responses to treatment and progress toward goals
- Authentications by the provider and applicable modifiers
It is important to document the number of minutes of each therapy code. CMS has mandated that total timed therapy codes and total treatment minutes be documented. A payer, facility, or other policy may require more detailed therapy documentation.
Assistant modifiers and the KX threshold
Two separate rules often get mixed into 8-minute-rule conversations.
CQ and CO modifiers
CQ and CO pertain to services performed by a PTA or OTA. Medicare evaluates these on a case-by-case basis, known as the de minimis rule. Medicare will consider allowing payment for services in which the assistant independently performed more than 10% of the service. There are exceptions to these rules.
It is important to review the actual minutes, codes and the CMS examples when a PT/PTA or OT/OTA splits a service. Modifiers are then to be reported based on the examples provided by CMS.
KX modifier
KX is neither a timed unit modifier nor a therapy cap. It is a modifier indicating that Medicare has determined the yearly expense for a specific service to be greater than its yearly cap and the beneficiary would no longer be eligible for reimbursement for that service. The attending clinician attests that the service is necessary and provides supporting justification. CMS has established a yearly cap of $2,480 for PT and SLP services combined and a separate yearly cap of $2,480 for OT services for 2026. CMS may revise its limits from one year to the next. Therefore, it is the responsibility of the providing clinician to become familiar with the caps for the year in which services are rendered.
Mistakes that create preventable denials
- Calculating each visit separately. Same-day, same-discipline timed minutes must be considered together for Medicare.
- Adding untimed services to the timed total. Evaluations, group therapy, and many other services have their own billing basis.
- Demanding eight minutes from every code. That is not how Medicare’s cumulative calculation works.
- Assigning units before calculating the total. Start with the daily unit limit, then allocate the codes.
- Assuming every payer follows Medicare. A payer manual beats office folklore every time.
- Treating KX as permission to bill more units. Medical necessity and correct unit calculation remain separate requirements.
- Using vague notes. “Thirty minutes of therapy” does not show the skilled services, clinical purpose, or patient response.
A pre-submission checklist for therapy claims
Before the claim leaves your system, confirm the following:
- The payer’s required time method is verified.
- Timed and untimed codes are separated.
- Eligible timed minutes are totaled by discipline and date of service.
- The unit count matches the CMS chart or the payer’s written method.
- Units are allocated to documented services in a defensible way.
- CQ, CO, GP, GO, GN, KX, and other modifiers are reviewed when applicable.
- The note supports medical necessity, services performed, time, and patient response.
Frequently asked questions
Does the 8 min rule apply to every CPT code separately?
Not under Medicare Part B therapy billing. Medicare determines the total number of timed units from combined eligible timed minutes for the same discipline and date, then assigns those units to the documented services. A payer using a code-by-code method may require a different calculation.
How many minutes equal three units under the 8 min rule?
Three units are supported by 38 through 52 total eligible timed minutes. At 53 minutes, the claim reaches four timed units under the Medicare chart.
Can leftover minutes from different CPT codes be combined?
For Medicare’s total-time therapy calculation, eligible timed minutes are combined by discipline and date of service. The final unit should then be allocated thoughtfully to the service with the greatest remaining documented time, subject to current CMS and payer guidance.
Do Medicare Advantage and Medicaid plans use the 8 min rule?
Some may, but you should not assume it. Check the patient’s specific plan manual, authorization requirements, and provider contract before you use the Medicare calculation.
Does the rule apply to group therapy or psychotherapy?
Not automatically. Group therapy is generally reported as an untimed service, while psychotherapy has separate code-specific time rules. Use the current descriptor and payer policy for the exact service being billed.
What might a patient see on an explanation of benefits?
A patient may see several therapy “units” on one date even when they had one appointment. Units describe the reportable services and timed treatment furnished, not necessarily the number of visits or separate copays.
