Calculators · Billing
8-minute rule calculator
This 8-minute rule calculator converts timed treatment minutes into billable units under the US Medicare rule, code by code.
Your numbers
Everything updates as you type. Nothing is uploaded.
Result
—
The formula
Total units = floor((total timed minutes − 8) ÷ 15) + 1, and zero below 8 minutes.
Thresholds fall at 8, 23, 38, 53, 68, 83, 98 and 113 minutes, and the pattern continues above two hours. To allocate, give each code one unit for every full 15 minutes. Then give any units still left to the codes with the most minutes remaining.
This is the US Medicare Part B method for outpatient therapy.
Worked example
22 minutes of code 1, 13 of code 2 and 9 of code 3 make 44 timed minutes, which is 3 units. Code 1 gets one unit for its first 15 minutes and has 7 left over. The two remaining units go to the codes with the most minutes left: code 2 (13) and code 3 (9). So each code bills one unit.
Common questions
Do I apply the rule to each code separately?
Not under Medicare. You total the timed minutes for the day, convert once, then allocate the units across the codes. Some commercial payers count each code on its own instead (an AMA CPT time convention), so check your payer’s policy.
Does a code with under 8 minutes count?
Its minutes still count toward the day’s total, and it can receive a unit if it has more minutes left over than the other codes. It can’t earn a unit on its own minutes alone.
Is this billing advice?
No. It is general information and arithmetic for the US Medicare rule, not billing, coding or legal advice. Your employer’s billing rules and your payer’s current guidance decide any claim.
Longer explanation: The 8-minute rule, explained without the jargon