Letter of Instruction

A letter of instruction is an informal, unwitnessed document left alongside an estate plan, addressed in practice to whoever will wind up your affairs. It typically records where the original will and other documents are kept, which accounts exist and at which institutions, who your professional advisors are, what obligations and subscriptions recur, and any wishes about a funeral or about particular personal belongings that do not belong in a will. It carries no legal force at all.

The same document is variously called a letter of intent, a letter of wishes or a side letter, and no issuing body appears to have settled a name for it. "Letter of instruction" is used here because the two commonest alternatives are already taken elsewhere in finance: a letter of intent is a commitment to invest enough in one fund family to reach a sales-charge breakpoint, and in commercial real estate it is the non-binding outline of a proposed purchase. Those are unrelated instruments, and a reader who searched for either would be in the wrong place. A related but distinct document is the letter a parent writes for whoever will care for a child with a disability, describing routines, preferences and medical history; that has a different audience and a different job, and it is not what this page covers.

The question worth answering here is not what belongs in the letter. It is whether the list you wrote is binding, and the answer is more interesting than "no."

Start with the general rule. A will can pull an outside document into itself by incorporation by reference, and the condition attached to it is one of timing. Minnesota's section 524.2-510 is the uniform text: "Any writing in existence when a will is executed may be incorporated by reference if the language of the will manifests this intent and describes the writing sufficiently to permit its identification." The writing must already exist at signing. A letter written afterwards cannot be incorporated, no matter how carefully the will gestures at it, which is precisely the shape of a letter of instruction that gets updated whenever something changes.

Then comes the exception, and it belongs to a different document. Most states' probate codes let a will refer to a separate signed list disposing of tangible personal property, and for that one narrow category the timing condition disappears: the list may be written after the will and altered afterwards. That instrument is the personal property memorandum, and its conditions, its exclusions and its conflict rule are set out on its own entry. The point for a reader here is only that it is a different document from this one. It is legally operative, it is narrow, and general-purpose guidance conflates the two constantly.

Which leaves the informal letter doing the job it is actually good at. Everything above is about moving property, and moving property is a small part of what an executor struggles with. The reliable failures in estate settlement are informational: an account nobody knew existed, a life insurance policy from a former employer, a safe-deposit box whose key is in a drawer, a storage unit on autopay, a domain name renewing annually against a card that has been cancelled. None of that needs legal force. It needs to be written down somewhere findable, and to be current, which is the one thing a witnessed document is bad at.

Two practical boundaries. Digital accounts have their own legal machinery, because an online provider's own tool for naming who may access an account generally outranks anything written in a will or a letter, and published digital estate planning covers that. And the letter should record where things are rather than the credentials themselves, because a document whose own contents are a security risk is one nobody can safely store where the executor will find it.

1. Write it as a finding aid. Where the original will is, who drafted it, which institutions hold which accounts, who the accountant and insurance agent are, what recurring obligations exist, and who should be told.

2. Keep the credentials out of it. Point at where access lives rather than reproducing passwords, and treat the provider's own legacy-contact tool as the operative mechanism for online accounts.

3. Keep it with the will, and date it. An undated letter found alongside two other undated letters helps nobody.

4. If you want specific belongings to go to specific people, ask whether your state has a separate-writing statute and whether your will refers to one. If it does, that list is the instrument to use, and it must be handwritten or signed and must describe items and recipients clearly.

5. Update the letter whenever the facts change, which is the entire reason it is not witnessed.

An example, working through what a single page accomplishes. Delia's will leaves her estate to her two children in equal shares and refers to a separate written list disposing of her tangible personal property. She signs the will in 2023, and in 2026 she signs a one-page list giving the sewing machine to her niece Beatriz and the framed prints in the hallway to her neighbor Tomás. Both gifts operate, even though the list postdates the will by three years. A third line on the same list, leaving the $9,000 in her credit union savings account to her niece, does nothing, because the separate-writing statute reaches belongings rather than balances; that $9,000 falls into the estate and is divided between the two children under the will, $9,000 ÷ 2 = $4,500 each. Why the third line fails, and what else the statute excludes, belongs to the personal property memorandum entry.

Delia also leaves a letter of instruction in the same envelope. It moves nothing. It says which credit union, that the old employer pension is with a successor administrator, that the storage unit is prepaid through March, and that the will was drafted by a firm that has since merged. Her executor finishes the estate months sooner because of the second document and receives no property under it whatsoever.

What it is good for

• It is the cheapest fix for the commonest problem in estate settlement, which is that the person in charge does not know what exists.
• It can be updated in minutes without witnesses, a notary or an appointment, so it can stay current in a way a will cannot.
• It can carry things that would be strange in a legal document: which photographs matter, what you would like said, who should be told first.
• It can point at the mechanisms that do have legal force, including the provider tools that govern digital accounts.

What it cannot do

• It binds nobody. An executor who ignores it entirely has broken no duty that arises from the letter.
• It cannot transfer property, override a beneficiary designation, or contradict the will.
• It cannot generally be incorporated into a will, because incorporation by reference reaches only a writing that already existed when the will was signed.
• The separate-writing statute that does have force is a different document and a narrower one, and it exists only where a state has enacted it and only where the will refers to a list.
• Left in a safe-deposit box, it can be unreachable during exactly the period it is needed.