By Brandon Seigel, Chief Problem Solver · September 8, 2026 · 6 min read
The CMS 8-minute rule
Medicare adds up all timed minutes for the visit, then converts the total to units: 8–22 minutes is one unit, 23–37 is two, 38–52 is three, and so on. Units are then assigned across codes based on minutes spent.
The AMA substantial portion rule
Many commercial payers follow CPT guidance instead. Each code stands on its own: a unit is billable when you pass the midpoint — at least 8 minutes of that specific code. Minutes are not pooled across codes.
Example: 7 minutes of 97110 and 7 minutes of 97530. Under CMS, 14 total minutes equals one billable unit. Under the substantial portion rule, neither code reaches 8 minutes, so neither is billable.
Know every payer's rule
Medicaid plans and commercial payers vary. The only safe approach is a payer-by-payer rule set applied to every claim before it goes out — which is exactly what daily claim review is for.
Quick answers
Do all insurance companies use the 8-minute rule?
No. Medicare uses the CMS 8-minute rule. Many commercial payers follow the AMA substantial portion rule, which counts each code separately.
Sources and further reading
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