An events business takes money months in advance and spends most of it in the last week. The books have to keep those two facts apart.
Revenue
Event or planning fee revenue. Venue or space rental revenue. Catering revenue where provided. Equipment and hire revenue. Commission or markup on suppliers booked on the client's behalf.
Supplier markup deserves its own line. It is a genuinely different margin from fee income, and it is where a lot of events businesses actually earn without realising how much.
Deposits are the whole cash story
A deposit taken twelve months before an event is not revenue — see deferred revenue.
Two things follow, and both matter more here than almost anywhere:
The money is committed to a future obligation. Spending it on running costs means the next deposit funds the last event, which works until bookings pause.
Cancellation is a real liability, not a lost sale. What is refundable and when should be visible rather than implicit.
Cost of delivery
Supplier and vendor costs, event supplies, decor and floral, staffing for the event, equipment hire, and transport.
Almost all of it lands in the final days, long after the deposit was banked — which is why working capital is the constraint on how many events a business can hold at once.
Overhead
Premises or storage, planning software, insurance, marketing and portfolio, admin wages.
What this setup gives you
The deferred balance against forward bookings, margin per event, and supplier markup as a visible line rather than a hidden one.