Two places that have sample letters of proposals include the University of Texas at Austin's McCombs School of Business website and the website of the business consultant Deiric McCann. In the business field, a letter of proposal provides background information on the proposed project or solution, shows why it is needed, outlines the benefits of the proposed solution to the client and tells how the solution will be carried out.
The contents of business proposal letters can vary. For example, the business proposal letter at the University of Texas at Austin's website is focused on an action plan for helping a non-profit organization, and it includes a few sections for background details, goals and procedures.
The sample letter at Deiric McCann's website is more detailed and includes an executive summary, an explanation of specific benefits, a description of how the solution will be carried out, a list of specific objects and a comprehensive list of benefits.