Medicare bills timed therapy codes in 15-minute units. Add up all the timed minutes in the visit: 8 to 22 minutes is 1 unit, 23 to 37 is 2, 38 to 52 is 3, and each further 15 minutes adds one more. Give each code a unit for every full 15 minutes, then give any remaining units to the codes with the most leftover minutes.
Use the free calculator to do this for any visit.
Key facts
| Who uses it | Medicare Part B outpatient PT, OT and speech therapy |
|---|---|
| Applies to | Timed CPT codes, such as 97110, 97112, 97140 and 97530 |
| Minimum for one unit | 8 minutes of total timed service |
| How minutes are counted | Pooled across all timed codes in the visit |
| Rule source | Medicare Claims Processing Manual, ch. 5, sec. 20.2 |
| Last checked | October 21, 2026 |
Minutes to units chart
The visit’s total timed minutes set how many units you can bill. The chart shows where each new unit begins.
| Total timed minutes | Units |
|---|---|
| Fewer than 8 | 0 |
| 8 to 22 | 1 |
| 23 to 37 | 2 |
| 38 to 52 | 3 |
| 53 to 67 | 4 |
| 68 to 82 | 5 |
| 83 to 97 | 6 |
The CMS method, step by step
Knowing the total units is half the job. You also have to decide which code gets each unit. CMS describes it this way.
- Add the timed minutes. Count only direct time spent providing timed services. Untimed services and time spent on notes before or after the patient are left out.
- Find the total units from the chart above.
- Assign full units. Each code gets one unit for every full 15 minutes it ran.
- Assign the rest by leftover minutes. If more units remain, they go to the codes with the most minutes left over after the full blocks.
- Check for ties. When two codes have the same leftover minutes, either may take the unit. Follow your Medicare Administrative Contractor’s guidance and apply one rule consistently.
Four worked examples
These follow the examples in CMS’s manual and in common billing references. You can load each one in the calculator.
A short service still earns a unit
| Code | Minutes | Full blocks | Leftover | Units billed |
|---|---|---|---|---|
| 97110 | 33 | 2 | 3 | 2 |
| 97140 | 7 | 0 | 7 | 1 |
| Total | 40 | 3 |
40 total minutes allow 3 units. 97110 gets 2 for its two full blocks. The third unit goes to 97140, whose 7 leftover minutes beat 97110’s 3, even though 97140 ran under 8 minutes.
The larger leftover wins
| Code | Minutes | Full blocks | Leftover | Units billed |
|---|---|---|---|---|
| 97112 | 24 | 1 | 9 | 2 |
| 97110 | 23 | 1 | 8 | 1 |
| Total | 47 | 3 |
47 minutes allow 3 units. Each code has one full block. The third unit goes to 97112, with 9 leftover minutes against 8.
Four short services
| Code | Minutes | Full blocks | Leftover | Units billed |
|---|---|---|---|---|
| 97110 | 8 | 0 | 8 | 1* |
| 97112 | 8 | 0 | 8 | 1* |
| 97140 | 8 | 0 | 8 | 0* |
| 97530 | 8 | 0 | 8 | 0* |
| Total | 32 | 2 |
32 minutes allow only 2 units, even though each service reached 8 minutes. All four codes tie at 8 leftover minutes, so any two may be billed. Under the rule of eights, the same visit would be 4 units.
A tie for the last unit
| Code | Minutes | Full blocks | Leftover | Units billed |
|---|---|---|---|---|
| 97110 | 18 | 1 | 3 | 1 or 2 |
| 97140 | 17 | 1 | 2 | 1 |
| 97530 | 18 | 1 | 3 | 1 or 2 |
| Total | 53 | 4 |
53 minutes allow 4 units. Each code gets 1 for its full block. The fourth unit goes to 97110 or 97530, which both have 3 leftover minutes; 97140 has 2.
* In example 3, which two codes are billed is a tie. The table shows one valid choice.
Medicare vs the rule of eights
Many commercial payers use the rule of eights instead. It comes from the CPT time rule: a unit is reached once its midpoint is passed. The difference is that each code is counted on its own, with no pooling.
| Medicare 8-minute rule | Rule of eights | |
|---|---|---|
| Minutes counted | Pooled across the visit | Per code |
| Code under 8 minutes | Can get a unit from leftover minutes | Never billed |
| Four codes of 8 minutes | 2 units | 4 units |
| Who uses it | Medicare Part B, and payers that adopt it | Many commercial payers |
Check each payer contract. Using the wrong method can underbill one payer and overbill another.
Timed and untimed codes
Only timed codes go into the minute count. Untimed codes are billed as one unit per session, however long they take. Their minutes still go into total treatment time in your note.
| Timed (counted) | Untimed (one unit) |
|---|---|
| 97110 Therapeutic exercise | 97161 to 97163 PT evaluations |
| 97112 Neuromuscular re-education | 97164 PT re-evaluation |
| 97116 Gait training | 97165 to 97167 OT evaluations |
| 97140 Manual therapy | 97168 OT re-evaluation |
| 97530 Therapeutic activities | 97150 Group therapy |
| 97535 Self-care training | G0283 Unattended electrical stimulation |
What to document
CMS’s documentation fact sheet lists what reviewers look for in outpatient therapy records. For timed codes, the essentials are:
- The total timed code treatment minutes for the visit.
- The total treatment time, including untimed services.
- A progress report at least once every 10 treatment days.
- A plan of care certified by the physician or practitioner within 30 days of the first treatment, and recertified at least every 90 days.
- Verbal orders documented and signed within 14 days.
Our plan of care calculator works out these dates for any patient. Source: CMS MLN905365, Complying with Outpatient Rehabilitation Therapy Documentation Requirements.
2026 KX and review thresholds
Units add up to dollars, and dollars trigger extra rules. For 2026, CMS set these amounts per patient per year:
| Threshold | PT and speech combined | OT |
|---|---|---|
| KX modifier required above | $2,480 | $2,480 |
| Targeted medical review above | $3,000 | $3,000 |
Services by a PT or OT assistant carry the CQ or CO modifier and are paid at 85%. Source: CMS, CY 2026 Therapy Services Updates. Check a patient with the KX threshold calculator.
What audits found
Federal auditors and prosecutors keep finding the same problems in therapy billing. These are public cases from other organizations, linked to the original reports.
of 300 sampled outpatient physical therapy claims did not meet Medicare requirements. OIG estimated $367 million in improper payments for July to December 2013.
Source: HHS OIG, A-05-14-00041 (March 2018)sampled patient days at one Northern California practice did not comply with Medicare rules, costing at least $583,000 in unallowable payments.
Source: HHS OIG, A-09-14-02040 (November 2016)paid by a Michigan therapy chain to resolve allegations that it billed one-on-one timed codes for group therapy from 2018 to 2024, when patients were treated in a group. The settlement resolves allegations.
Source: US Attorney’s Office, Eastern District of Michigan (March 2026)Common mistakes
- Billing each code on its own for Medicare. This is the rule of eights, and it often overbills Medicare.
- Counting untimed minutes. Evaluation time does not add timed units.
- Counting note-writing time. Only time spent with the patient counts.
- Billing one-on-one codes for group sessions. Group therapy is 97150.
- Notes that don’t match the claim. Total timed minutes in the note must support the units billed.
Questions
Does the 8-minute rule apply to every payer?
No. It is Medicare’s method for timed outpatient therapy codes. Medicare Advantage plans, Medicaid programs and commercial payers set their own rules: some follow the Medicare method and many commercial payers use the rule of eights. Your payer contract decides.
Is 7 minutes ever billable?
On its own, no. Under Medicare, a service with fewer than 8 minutes can still receive a unit when the visit’s total timed minutes support it and that service has the most leftover minutes.
How many units is 60 minutes?
Four units. 53 to 67 total timed minutes equal 4 units under Medicare.
Do minutes spent writing notes count?
No. Only time spent providing the service to the patient counts. CMS says pre- and post-delivery work is not counted toward treatment time.
Does the rule apply to group therapy?
No. Group therapy is billed with the untimed code 97150, once per patient per session. Timed codes require direct one-on-one contact.
Sources
- CMS, CY 2026 Therapy Services Updates
- CMS Medicare Claims Processing Manual, chapter 5, section 20.2
- CMS MLN905365, Complying with Outpatient Rehabilitation Therapy Documentation Requirements
- HHS OIG, A-05-14-00041 (March 2018)
- HHS OIG, A-09-14-02040 (November 2016)
- US Attorney’s Office, Eastern District of Michigan (March 2026)
- APTA, Medicare therapy threshold
This guide gives general information, not billing or legal advice. Rules can differ by payer and Medicare Administrative Contractor. Last checked October 21, 2026.