The invoice charges seats, not visits
A ChatGPT Business workspace bills the paid seats you committed to. Eight seats with three people who never open the chat still invoice as eight, until an owner schedules the reduction.
Seats already committed for the monthly or annual cycle are not refunded because they sat idle. A reduction applies to later cycles.
Removing a person leaves the seat paid
Removing a member frees that seat so you can assign it to someone else. The paid seat count stays put until you reduce it in billing.
The reduction starts at the next billing cycle, not the same day. Unassign people first: you cannot drop the count below seats that are still occupied. Adding seats is charged immediately, prorated through the end of the cycle.
Chat and the API are two invoices
ChatGPT Business does not include API usage. A team can have idle seats and, in the same month, a token invoice from an agent or an app. Cutting seats does not touch that second bill.
Workspace credits and spend caps limit extra usage. They do not replace a count of how many seats you are paying for.
What to compare this week
Put paid seats in one column and people who actually sign in in the other. Schedule the spare seats for the next cycle and check billing to confirm the reduction is recorded.
If the same month you also pay for Claude, Copilot, or an API, an auditamia report lines those invoices up with the export you pull yourselves. We do not log into the account. From €99, in 48 hours, with a verdict per tool: keep, reduce, cancel, or watch.