A will trust (or a testamentary trust) is a trust which arises upon the death of a testator, and which is specified in his or her will. They are distinguished from inter vivos trusts, which are created during the settlor's lifetime. Will trusts come into effect on death.
A will trust is a legal entity created as specified in a person's will, and is occasioned by the death of that person. It is created so that the testator's estate, which has been accumulated during his lifetime, can be dealt with according to his wishes. A trust can be created to oversee such assets, in circumstances where the settlor does not want his estate distributed in its entirety on his death. A trustee is appointed by the will to manage and administer the trust until a set time when the trust expires, often when minor beneficiaries reach a specified age, or accomplish a deed such as completing a degree or becoming married.
For a will trust, as the settlor is deceased, he or she will generally not have any influence over the trustee's exercise of discretion, though it is common for the testator to leave a letter of wishes for the trustee's consideration. In practical terms, a will trust tends to be driven more by the needs of the beneficiaries (particularly infant beneficiaries) than by tax considerations.