A letter (also called a memorandum of wishes) written by the settlor of a trust to the trustees, to guide them as to how the settlor would like the trust to be administered. A letter of wishes is not binding on the trustees and often accompanies a discretionary trust, where the trustees may be in need of guidance.

A letter of wishes may also accompany a will, to enable the testator to guide the executors where they have an element of discretion over a gift.