Medicare timed-code worksheet

8 Minute Rule Calculator

Enter total timed therapy minutes or break minutes out by CPT code to estimate Medicare billable units under the 8-minute rule.

PT / OT timed codesUnit intervalsService allocation

Live calculator

Calculate 8-minute rule units

Use only timed-code treatment minutes for the date of service. Exclude untimed evaluations.

For Medicare 15-minute timed therapy codes, 8-22 minutes supports 1 unit, 23-37 minutes supports 2 units, and each additional unit starts after another 15 minutes.

Rule guidance

What the 8-minute rule calculator is applying

This 8 minute rule calculator follows the Medicare timed-code structure for outpatient rehabilitation therapy. It is a planning aid, not a replacement for payer policy, documentation review, or billing compliance judgment.

For one 15-minute timed code on a date of service, fewer than 8 minutes does not support billing that timed service.

The total timed-code treatment minutes determine the maximum number of timed units for the day when multiple 15-minute timed services are furnished.

Untimed-code services, such as many evaluations, are not counted toward timed-code units.

Commercial payers, Medicaid programs, Medicare Advantage plans, and employer policies may apply different billing instructions.

Sources & review

CMS Medicare Claims Processing Manual, Chapter 5Review the current CMS manual for outpatient rehabilitation payment and timed-code unit guidance.

Unit chart

8-minute rule chart for timed therapy codes

Use this chart to sanity-check the 8 minute rule calculator result. The first billable unit starts at 8 minutes. After that, each additional unit begins at the next 15-minute interval.

UnitsTimed minutesPlanning note
1 unit8-22 minutesFirst billable timed-code unit.
2 units23-37 minutesOne more billable unit than the 1-unit interval.
3 units38-52 minutesOne more billable unit than the 2-unit interval.
4 units53-67 minutesOne more billable unit than the 3-unit interval.
5 units68-82 minutesOne more billable unit than the 4-unit interval.
6 units83-97 minutesOne more billable unit than the 5-unit interval.
7 units98-112 minutesOne more billable unit than the 6-unit interval.
8 units113-127 minutesContinue the same pattern above 2 hours.

Examples

8-minute rule examples that prevent common billing mistakes

The most common mistake is counting each short service as a separate unit. Medicare constrains total timed-code units by total timed minutes for the date of service.

ScenarioMinutesUnitsWhy it matters
Short single service7 timed minutes0 unitsA single 15-minute timed code needs at least 8 minutes before one unit is supported.
First billable unit8 timed minutes1 unitEight minutes reaches the midpoint threshold for the first timed-code unit.
Four short services32 total timed minutes2 unitsFour separate 8-minute treatments do not create 4 units because the total minutes fall in the 23-37 minute range.
Two timed codes24 min 97112 + 23 min 971103 unitsThe total is 47 minutes, which supports 3 units. Allocate the extra unit to the service with the larger remainder.

Method

How to use the 8 minute rule calculator correctly

Separate timed and untimed services

Count only minutes tied to 15-minute timed CPT or HCPCS services. Do not add evaluation minutes or other untimed services to the timed-code total.

Use the total timed minutes first

When more than one timed service is furnished on the same date, calculate the total units from total timed-code treatment minutes before assigning units to individual codes.

Allocate units after full 15-minute blocks

A service performed for at least 15 minutes generally supports at least one unit. Remaining units are usually assigned to the service with the largest remaining minutes.

Keep documentation defensible

The calculator cannot determine medical necessity, payer-specific edits, modifiers, assistant involvement, or whether the note supports the billed units.

EEAT notes

Why this calculator includes compliance context

Billing-unit math is simple, but claim accuracy depends on documentation, payer rules, therapist versus assistant involvement, and whether each service is timed or untimed. This page includes edge cases and allocation notes so the 8 minute rule calculator gives more than a raw number.

Content reviewed September 9, 2026.

This tool is for educational planning only. Confirm final billing decisions with your organization, payer contracts, Medicare Administrative Contractor guidance, and qualified billing or compliance staff.

FAQ

8-minute rule calculator questions

What is the 8-minute rule?

The 8-minute rule is the Medicare timed-code billing method for many outpatient therapy services measured in 15-minute units. A final timed unit is supported when the remaining treatment time reaches at least 8 minutes.

How many units is 40 minutes under the 8-minute rule?

Forty timed-code minutes supports 3 units because 40 minutes falls in the 38-52 minute interval.

Does 7 minutes count as one unit?

A single timed service performed for 7 minutes does not support one unit. If multiple short timed services are furnished on the same date and the total reaches at least 8 minutes, the total timed minutes may support one unit assigned to the service with the most minutes.

Do untimed evaluations count toward 8-minute rule units?

No. Untimed-code services are billed as their own unit rules allow and should not be added to timed-code treatment minutes.

Can this 8 minute rule calculator allocate units across CPT codes?

Yes. The service-line mode estimates allocation by calculating full 15-minute blocks first, then assigning remaining units to the services with the largest remainder. Treat the allocation as a planning aid because payer and documentation facts can change the final claim.

Therapy productivity context

Keep billing units and productivity planning separate

Timed-code units answer a billing question. These resources explain the separate counted-work-time definition used in therapy productivity planning.

Therapist Productivity Calculator

Calculate a productivity percentage, required billable minutes, or a target end time.

Open resource

Therapy Productivity Formula

See the billable-minute and counted-work-time formulas with worked examples.

Open resource

Billable vs Non-Billable Therapy Minutes

Separate treatment, counted non-billable work, and unpaid time before planning.

Open resource

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