Discover what a bid proposal is, the elements of a bid proposal, how to create one and a template and example that can guide you. Thirty days advance written notice of cancellation to County - General Liability,.The time and place of the bid letting is published in the letting's Bid Solicitation Notice(s), (Notice to Contractors). A tactful letter rejecting a bid informs the bidder of your decision, but still leaves the door open for future business. The three types of competitive procurement are the Invitation to Bid, the Request for Proposals, and the Letter of Interest process.