A construction proposal is a document used to provide a client with a clear understanding of a project's details. Class B General Contractor's License in good standing with the State of California is required.TL;DR: Get detailed proposals with scopes of work from contractor(s). How do I fill this out? I had a General Contractor ask that I give them a "letter of introduction" for my company to be put on a bid list. Comply with California law! Professional Proposals meet State laws and regulations, with plenty of room to write in costs and specifications.