The 8-minute rule for PT billing, with worked examples

Under Medicare, you bill timed therapy codes by the total minutes of timed treatment in the day, not by the minutes of each code. Eight minutes is the smallest amount that earns one unit. Once your clinicians record minutes per code, the rest of the rule is arithmetic you can do at the front desk.

These rules apply to Medicare and to 15-minute timed codes. Other payers may follow a different method, covered further down.

The conversion table

CMS's Medicare Claims Processing Manual gives the time intervals for 1 through 8 units of a 15-minute timed code, and says the pattern stays the same beyond 2 hours.^[1] When only one service is provided in a day, CMS says providers should not bill for services performed for less than 8 minutes.^[1]

The rules that decide your units

• Total minutes cap the units. If more than one 15-minute timed code is billed on a day, the total number of timed units is constrained by the total treatment minutes for that day.^[1]
• 15 minutes earns a unit. A timed service performed for at least 15 minutes is billed for at least one unit, and at least 30 minutes for at least two. It is not appropriate to count all minutes toward one code if other services ran more than 15 minutes.^[1]
• Extra units go to the service with more time. CMS's examples give each code one unit for every full 15 minutes, then assign any remaining units by comparing the minutes left over (Examples 1 and 3 below).^[1]
• Short services can combine. If two or more timed services were each performed for 7 minutes or less and together they reach 8 minutes or more, bill one unit for the service performed for the most minutes.^[1]
• Document the total. CMS says the total number of timed minutes must be documented.^[1]

Worked examples from CMS

These come from the CMS manual's own examples.^[1] Codes: 97110 therapeutic exercise, 97112 neuromuscular reeducation, 97116 gait training, 97140 manual therapy, 97035 ultrasound.

Timed and untimed codes

The rule only applies to timed codes. CMS's unit-limit chart no longer has a timed or untimed column, because the notation is not relevant to the number of units allowed per code.^[1] The code descriptor is the practical guide: ASHA says timed codes include a specific time designation in the descriptor, such as "each 15 minutes."^[9] For untimed codes CMS says providers enter 1 unit, regardless of how many minutes the service took.^[1]

How the CPT midpoint rule differs

APTA says there is "a distinct difference" between Medicare's 8-minute rule and the "passing the midpoint" standard in the CPT manual. The CPT guidelines do not require adding up total minutes, so a therapist could bill one unit of a service each time the midpoint is passed for that unit.^[7] ASHA puts it the same way: the two are different methodologies, and Medicare's rule applies only to 15-minute timed codes.^[9]

An illustration: a patient gets 8 minutes of 97110 and 8 minutes of 97140, 16 timed minutes in all. Under the Medicare table, 16 minutes is 1 unit. Under a midpoint approach, where a unit is reached once more than half of the 15 minutes is spent, each 8-minute service reaches its own unit, so a payer that follows CPT could allow 2.

Payers do not all agree, and they change their policies. APTA notes that a payer contract can override these standards: if a contract lets you bill additional units after 5 minutes, the contract takes precedence.^[7] Keep a payer-by-payer rule sheet, and check it when a payer updates its policy.

Anthem is one example. APTA reported in September 2025 that it had objected to an Anthem policy that merged the CMS 8-minute rule with the AMA midpoint rule. APTA says Anthem then dropped the requirement to document start and stop times for each CPT code in a revision effective August 13, 2025, and now asks for total treatment time for each modality. APTA also said it was still working to align Anthem California.^[8]

Modifiers and thresholds that touch your claims

• KX modifier. For calendar year 2026 the KX threshold is $2,480 for physical therapy and speech-language pathology services combined and $2,480 for occupational therapy.^[2][3] The modifier confirms the services are medically necessary as justified by documentation in the record.^[2][3] Claims above the threshold without KX are denied.^[2][3] When Medicare denies payment for a missing KX, CMS's Benefit Policy Manual says the therapist or provider is financially liable unless a valid Advance Beneficiary Notice (ABN) transfers liability to the patient.^[5]
• Medical record (MR) threshold. CMS also keeps a $3,000 medical record threshold. The KX amounts are updated each year, and the $3,000 MR threshold stays at $3,000 until CY 2028.^[2] This article reflects CMS's calendar year 2026 update as of September 2026, so check the current transmittal.
• CQ modifier. Outpatient PT services furnished in whole or in part by a physical therapist assistant (PTA) use the CQ modifier, paired with the GP therapy modifier.^[1][4] On professional claims, CMS's claims manual limits the modifier to services of physical and occupational therapists in private practice.^[1] For dates of service on or after January 1, 2022, those claims are paid at 85% of the otherwise applicable amount, a 15% reduction.^[1] CMS applies a 10% standard: the modifier is used when the PTA's minutes for a service or unit exceed 10% of the total minutes for it.^[4]

Plan of care certification

Under 42 CFR 424.24(c), outpatient therapy needs a certification by a physician, nurse practitioner, clinical nurse specialist or physician assistant. The initial certification must be obtained as soon as possible after the plan is established, and recertification is required at least every 90 days, with the record showing the continuing need for therapy.^[6] CMS's Benefit Policy Manual defines "as soon as possible" as within 30 days of the initial therapy treatment, and allows a plan to be certified for up to 90 calendar days.^[5] A late or missing certification can put claims under that plan at risk, so track the dates the same way you track units.

Where to go next

Timed units, modifiers and payer-specific rules add up across a full schedule. Time-based coding matters in other specialties too, as our guide to psychotherapy billing time rules shows. See how we handle physical therapy billing and denial management, or request a free billing audit to review your last quarter of claims.