This guide is designed to teach you how to write a letter of instruction for heirs, or anyone else who may benefit from a little more direction. A letter of instruction is a cheat sheet for anyone involved in settling your affairs.Unlike a will, this letter has no legal authority. Member Service Center (707) 449-4000 or (800) 877-8328 Monday – Friday: 8 am – 7 pm (PDT) Saturday: 9 am – 5 pm In this blog post, we'll delve into what a letter of instruction is, why it's essential, and how to craft one with finesse and ease. A personal letter of instruction to loved ones, children, trustees, agents and others is a critical step in your estate plan. Required Documents: Signed Letter of Instruction, 1 Original Writ, 1 Copy of Writ. Upon receiving approval for an INTER-District application, you have 48 hours to complete online enrollment before your application is waitlisted. Open a TCU Checking Account, or, if you already have one, skip to step 2. A letter of instruction, or letter of intent, is a simple document that can take the guesswork and headache out of settling your estate.