If you bill Medicare Part B for outpatient therapy in 2026, the 8-minute rule decides how many units you can charge for every timed treatment, from 97110 therapeutic exercise to 97140 manual therapy. This guide is for physical therapy practice owners, billers and clinicians who want to bill accurately and avoid denials. You will learn the unit chart, which codes count toward it, how to combine several codes in one visit, and the mistakes that lead to underbilling and audits.
Key Takeaways
- The 8-minute rule is how Medicare counts units for timed codes, which are billed in 15-minute increments.
- You need at least 8 minutes of timed treatment in total to bill one unit.
- Add up all timed minutes for the day. Do not apply the 8-minute threshold to each code on its own.
- 8 to 22 total timed minutes equals 1 unit, 23 to 37 equals 2 units, and 38 to 52 equals 3 units.
- Untimed codes, such as evaluations and hot or cold packs, do not count toward your timed minutes.
- When you bill several timed codes, the extra units go to the services with the most minutes.
- Many commercial payers follow different rules, so check each payer's policy.
- Document total timed minutes, total treatment time and the minutes for each timed service in every note.
- Applying the rule wrongly can cause denials and audits on one side, and uncollected revenue on the other.
What Is the 8-Minute Rule in Physical Therapy?
The 8-minute rule is the method Medicare uses to turn treatment minutes into billable units for timed CPT codes. A timed code describes a service measured in 15-minute increments. Instead of billing one unit per service, you add up every timed minute you spent with the patient and use that total to find the units you can bill.
Where the Rule Comes From
The counting method is set out in the Medicare Claims Processing Manual, Chapter 5, Section 20.2. You can read the current text on the CMS website. The American Physical Therapy Association also explains how timed codes work in its coding guidance for timed codes.
Who It Applies To
The rule applies to Medicare outpatient therapy claims. Other payers may use it, adapt it or use a different method, which is why you should always read each payer's billing policy.
The Medicare Unit Chart
Use your total timed minutes for the day to find the number of units:
| Total timed minutes | Units you can bill |
|---|---|
| 8 to 22 minutes | 1 unit |
| 23 to 37 minutes | 2 units |
| 38 to 52 minutes | 3 units |
| 53 to 67 minutes | 4 units |
| 68 to 82 minutes | 5 units |
| 83 to 97 minutes | 6 units |
| 98 to 112 minutes | 7 units |
| 113 to 127 minutes | 8 units |
The pattern continues in 15-minute steps. Fewer than 8 total timed minutes means you cannot bill a timed unit for the visit.
Timed vs Untimed Codes: What Counts?
Only timed codes go into the minute total. Mixing the two is one of the most common sources of billing errors.
Common Timed Codes
- 97110: therapeutic exercise
- 97112: neuromuscular re-education
- 97116: gait training
- 97140: manual therapy
- 97530: therapeutic activities
- 97535: self-care and home management training
Common Untimed Codes
- 97161 to 97163: physical therapy evaluations
- 97164: physical therapy re-evaluation
- 97010: hot or cold packs
- 97012: mechanical traction
Untimed services are generally billed once per visit, no matter how long they take. Their minutes are not added to the timed total. Always confirm the code's current descriptor, because a few codes are described differently by different sources.
How to Count Units Across Multiple Codes
Step by Step
- Record the minutes of each timed service.
- Add the minutes of all timed services together.
- Use the unit chart to find the total units for the day.
- Give full 15-minute units to services with 15 or more minutes.
- Give any remaining units to the services with the most leftover minutes.
- Add any untimed code once.
Worked Example: 33 Timed Minutes
A patient receives 20 minutes of therapeutic exercise (97110), 13 minutes of manual therapy (97140) and a 10-minute hot pack (97010).
- Timed minutes: 20 + 13 = 33 minutes, which is 2 units.
- 97110 has a full 15 minutes, so it takes 1 unit. 97140 takes the second unit.
- The hot pack is untimed, so it is billed once and does not count toward the 33 minutes.
- Result: 1 unit of 97110, 1 unit of 97140 and 1 unit of 97010.
Worked Example: 28 Timed Minutes
A patient receives 20 minutes of 97110 and 8 minutes of 97530. The total is 28 minutes, which is 2 units. The first unit goes to 97110. After that, 97530 has 8 leftover minutes and 97110 has 5, so the second unit goes to 97530.
The Under-8-Minute Case
If a visit includes only 7 minutes of timed treatment in total, there is not enough time to bill a timed unit under Medicare's rule.
Common 8-Minute Rule Mistakes
- Applying the rule to each code separately. Add up all timed minutes first, then apply the chart.
- Counting untimed minutes. Evaluations and modalities like hot packs stay out of the timed total.
- Rounding up. 7 minutes does not become 8, and 22 minutes does not become 23.
- Missing documentation. If the note does not support the minutes, the units are at risk in an audit.
- Assuming every payer uses Medicare's method. Some commercial payers use a different approach.
- Leaving units unbilled. Under-billing earned units is lost revenue, and it adds up across hundreds of visits.
If You... Scenarios
If You Are a Solo Practice Owner
You are probably billing between patients. Set up a simple habit: record the minutes for each timed service right after the session, and let your EMR calculate the units from the total. Then review a sample of claims each month against your notes.
If You Use PTAs or Mixed Staffing
When a physical therapist and a physical therapist assistant both provide parts of a timed service, CMS still uses the 8-minute rule to determine the final unit, and the CQ modifier may apply. See the CMS billing examples for CQ and CO modifiers for details.
If You Bill Commercial Payers
Do not assume Medicare's chart applies. Check each payer's policy, because some use a different method for counting timed units. Keep a one-page cheat sheet of the rule each major payer uses.
If You Are Behind on Billing or Denials
Unit-count errors are a common reason claims are delayed or denied. If you are spending your evenings on billing, a billing partner that understands the rule can take it over. You can see real results from PT practices or read answers to common billing questions.
Frequently Asked Questions
What is the 8-minute rule in physical therapy?
The 8-minute rule is the way Medicare counts units for timed therapy codes. You add up all the timed minutes you provide in a visit, then use a chart to find the number of units you can bill. You need at least 8 minutes of timed treatment in total to bill one unit. Each additional unit requires another block of minutes, so 8 to 22 minutes is 1 unit, 23 to 37 minutes is 2 units, and so on in 15-minute steps. The rule is set out in Chapter 5 of the Medicare Claims Processing Manual. Untimed services, such as evaluations and hot or cold packs, are not counted toward the total.
Does the 8-minute rule apply to commercial insurance?
Not always. The rule comes from Medicare, and many commercial payers use it, but some use a different method for counting timed units. A payer may follow its own policy or a rule from another organization. Because the differences can change how many units you are paid for, check each payer's published billing policy or ask your provider representative. It helps to keep a short reference sheet for your top payers so that your clinicians and billers apply the right method every time. If you are unsure, ask the payer in writing and keep the answer on file. That written answer protects your practice if a claim is questioned later and saves your team from guessing.
Do untimed codes count toward the 8-minute rule?
No. Only timed codes are added to the minute total. Untimed codes, such as the physical therapy evaluation codes 97161 to 97163, the re-evaluation code 97164, hot or cold packs (97010) and mechanical traction (97012), are generally billed once per visit regardless of how long they take. Their minutes are not added to the timed total, and they do not change the number of timed units you can bill. When you review a claim, list timed and untimed services separately so the total is easy to check. Always confirm the current descriptor for any code you are unsure about, and make sure your EMR is set up to treat each code as timed or untimed correctly, because a wrong setting can quietly affect every claim.
How many units can I bill for 30 minutes of therapy?
If all 30 minutes are timed treatment, the Medicare chart gives you 2 units, because 30 falls within the 23 to 37 minute range. If some of those 30 minutes were an untimed service, such as an evaluation or a hot pack, subtract those minutes first, and then use only the timed minutes to find the units. For example, 30 total minutes with 10 minutes of hot pack leaves 20 timed minutes, which is 1 unit plus 1 unit of the untimed hot pack code. Counting the right minutes is what keeps the claim accurate. A good habit is to write the timed and untimed minutes separately in the note, so anyone reviewing the visit can see how the units were calculated.
What happens if I bill the wrong number of units?
Billing too many units can lead to denials, payment recoupment and audits. Billing too few means you are leaving money you earned uncollected. Either way, accuracy depends on good documentation. Your notes should show the minutes for each timed service, the total timed minutes and the total treatment time. A short monthly review of a sample of claims against the notes can catch patterns before they become a problem. If you find unit errors, correct them and talk to your compliance resource or billing partner about the right way to fix past claims. Do not simply change old notes, because documentation should always reflect what actually happened during the visit.
About Physical Therapy Billing
Physical Therapy Billing is a revenue cycle management company built and run by eight physical therapy practice owners. We know the 8-minute rule because we have applied it in our own clinics. We only charge for what we collect, and we offer a free profitability audit that shows where a practice's revenue may be leaking. Learn more about our story, hear what clients say or try our AR calculator.
For a free profitability audit, visit physicaltherapybilling.com/schedule-your-analysis.
This article is for general education and is not legal, coding or compliance advice. Billing rules change and vary by payer, so confirm them with the payer and the current CMS manual.