Where the requirement hides
Venue vendor agreements, catering contracts and event permits each carry insurance language, and they do not always agree. When a planner, a venue and a municipality are all involved, the strictest version governs what you must show.
The alcohol question
Liquor liability is where venue certificates most often fail. Venues want to see it as a separate line with a limit, naming the venue, and valid off the vendor's own premises. If your policy ties alcohol service to your restaurant address, you need an endorsement or a separate liquor policy before you pour at an event.
Timing
Venues want certificates before load-in and frequently a week before the event so the compliance file is complete. Planners collect them from every vendor and chase the late ones. A live certificate link turns this from a per-event errand into a one-time share.
What to send the venue
A certificate with the venue, owner and management company as additional insured on general liability and liquor liability where applicable, auto if you bring a vehicle onto the property, workers' compensation, and an umbrella where required, with the endorsement forms referenced and the event date in the description where the venue asks for it.