In this article, we discuss how to write a business proposal letter and we offer sample letters and templates you can use as a guide. 3. Proposals should be concise and complete. .4.The following is a suggested format: a. 1 Name of business entity filing form, and the city, state and country of the business entity's place of business. • Proper and valid licensing to conduct business in the State of Florida. • Current Department of Professional Regulation License(s). 1. Acceptance shall be provided to the successful proponent in the form of a letter. A business proposal letter is a document sent to a prospective client or partner, introducing your services or requesting an opportunity. This form shall be completed and submitted with your proposal.