The 40-60% TCO underestimate on enterprise agentic-AI deployments is not a cost-visibility failure — it is a cross-departmental cost-attribution failure. Integration, tokens, maintenance, supervision, and compliance costs land on IT, HR, and Legal budgets that do not reconcile in most organisations, so the CFO sees the bill late and partial.

Based on 2026 CFO-guide data: €368K vs €158K naive estimate, 40-60% TCO underestimate, 73% exceed by 2.4x, 15-20%/year maintenance, supervision tax in thousands/month, 70% failure from change management. Watching for a Big 4 TCO framework or enterprise CFO survey that resolves the cross-departmental framing.