All vendors submitting bids and offers on Illinois public contracts must: 1. Be a legal entity authorized to transact business or conduct affairs in Illinois.Bid Deposits: When specified in an advertisement, bids must be submitted with a deposit, i.e. Cashier's check, certified check, money order or bid bond. When bidding for a recognized opening, please remember to enter the unit notice number. A written request for bid contains a complete description of the commodity or service requested and the quantity required. How do I fill out Schedules C and D? Please follow the directions in the bid document or contact the DBE department should you need additional assistance.