Open Billing → Receivables → Proformas. Use the proforma as a controlled review of work that may become an invoice.
Check the customer or account, included trips, service dates, amounts, taxes or additions, and any visible payment context. Compare the result with the originating reservations and the company’s billing policy.
Resolve unexpected items before advancing the billing workflow. A proforma is not a substitute for correcting the underlying reservation when the reservation itself is wrong.