The final guest count (in Italian, numero definitivo) is the number of guests you give the caterer by a date set in the contract, usually a few weeks before the event. On that number the caterer orders ingredients, organises staff and prepares the invoice.
After the deadline the number can often go up, sometimes with a supplement, but not down. Read it together with the guaranteed minimum and any tolerance. The seating plan, the list of diets and the table plan also depend on that date.
How to organise it
Set your guests' RSVP deadline a few days before the contract date, so you have time to chase anyone who has not replied. Ask how children, staff and suppliers are counted. The deadlines are in the guide to the event timeline and the guide on what to check in the contract.
