How To Write A Contract Proposal Letter . The proposal template below is written to show you what a generic proposal business letter might look like. It should be written in the format of a formal business letter and mailed by certified mail. Service Contract Proposal Template from ikase.us In the first paragraph, address the subject of your proposal. This bid is actually the price you’d sign the contract for. In other words, write a business proposal outline that is easy to glance over and that highlights your value proposition.