A letter of instruction is a document that lists all relevant financial information that your family members or executor need if something happens to you. A letter of instruction is a cheat sheet for anyone involved in settling your affairs.Unlike a will, this letter has no legal authority. Writing a letter of instruction can help expedite the estate planning process. Learn exactly how to write a letter of instruction for heirs and executors here. What goes in a letter of instruction? You can provide care for your pet using many strategies, such as creating a Trust, appointing a guardian, choosing a pet care organization, etc. A letter of instruction can complement an estate plan and provide your loved ones with additional details about your assets and wishes after death. Have you made provisions in your will for your dog or cat to be cared for if you die first? CA is one of several states which lets residents name guardians or create trusts to ensure a pet is well cared for after their owners die.