Why AI spend is unattributable by default

The invoice grows and nobody can say which team caused it. That is the default, and it is structural.

How it happens

• One shared API key per provider.
• Keys copied between teams.
• No team or app on the request.
• A separate invoice per provider.
• Self-hosted models metered by nobody.

Why spreadsheets fail

Asking teams to log their usage decays within weeks. New apps inherit old keys.

The fix

• All model traffic through one gateway.
• Team, app and user on every request.
• Budgets enforced at the gateway.
• Telemetry in the monitoring you already run.

The result

Finance gets chargeback it can defend. Teams get budgets they control. The question becomes whether the spend was worth it.