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. Instantly draft and send a business proposal template to establish the terms and conditions between your business and clients.Cover letter – This letter should introduce the proposal and include the specific request amount. Download Texas Business Proposal template, modify and send for signing using BoloForms Signature. • Make your RFP easier to read and qualify by. The PI will need to complete the basic information of their proposal and provide a short summary description of their proposed project. A business proposal letter is a document sent to a prospective client or partner, introducing your services or requesting an opportunity. Authorized to do business in the State of Texas.