Irrevocable trusts are a type of trust fund that cannot be changed by the grantor after the assets are placed in the trust. The grantor (the person creating the trust) gives up all control and ownership of the property placed in it. Signing over the property in this way has significant tax advantages since the value of the "gift" of the assets is sometimes tax deductible. The grantor may still be paid income from such a trust each year until his/her death. Irrevocable trusts can be created to protect assets by placing them out of reach of creditors. For example, a grantor might make his/her spouse or child the beneficiary of the trust. Since the grantor no longer has any claim to or ownership over the assets in the fund, they cannot be seized to collect a debt.

Often, a grantor will choose to create a revocable trust that converts to irrevocable status upon the grantor's death. The terms of an irrevocable trust can last more than one generation - effectively giving the grantor the ability to dictate how the funds are administered for many decades. Some individuals place restrictions on the distribution to beneficiaries in order to encourage responsible behavior. For example, the terms of the trust might state that all access to the trust is cut off if the beneficiary becomes addicted to drugs or refuses to hold a job.