Download a letter of intent to sue (with settlement demand) to inform a defendant that you will sue if they don't pay a settlement amount. This article explains what demand letters are, when they are useful, and how to write them.A letter of intent to sue (with settlement demand) notifies an individual that the sender intends to file a lawsuit against them. In this article, we discuss how to write a demand letter, what to include in a demand letter, and provide a Texas demand letter template. Are you suing them in their state? Settlement demand letters are used in most personal injury cases to begin settlement negotiations.