Q: What's the difference between a copay and coinsurance for therapy?
A: A copay is a flat fee per session — for therapy, typically $0–40 on California plans. Coinsurance is a percentage of the plan's negotiated rate, usually after your deductible. Same plan document, very different math.
Worked example: plan A charges a $30 copay → 20 sessions = $600/year, predictable. Plan B charges 20% coinsurance on a $120 negotiated rate after a $1,500 deductible → roughly $1,500 + (20% × $120 × remaining sessions) ≈ $1,700+ in year one.
Do this: ask your plan: "For CPT code 90834, outpatient mental health, in-network — do I pay a copay or coinsurance, and is the deductible waived?" Asking by code number gets a real answer.
Source: TherapyCalifornia insurance routes, August 2026.