An irrevocable trust is a trust that cannot be amended, modified, or terminated by the grantor, settlor, or trustor (person who created the trust) after it is created—at least not without the permission of the beneficiary or beneficiaries.

Irrevocable trusts generally offer tax benefits that revocable trusts do not. This is primarily because the grantor, settlor, or trustor who creates an irrevocable trust permanently transfers (gifts) all right of ownership of the assets to the trust and its beneficiaries.

Laws vary from state to state but a trust is usually irrevocable unless the grantor, settlor, or trustor specifies otherwise in the trust agreement.

In Utah, an irrevocable trust is a type of trust that, once established, cannot be changed, modified, or terminated by the person who created it, known as the grantor, settlor, or trustor, without the consent of the trust's beneficiaries. The main characteristic of an irrevocable trust is the transfer of ownership of assets from the grantor to the trust, which is managed for the benefit of the beneficiaries according to the terms set out in the trust agreement. This transfer is considered complete and permanent, which can provide certain tax advantages, such as reducing the grantor's taxable estate, since the assets are no longer considered part of the grantor's property. In Utah, as in other states, the terms of the trust are governed by the trust agreement, and unless the trust document explicitly states that the trust is revocable, it is generally presumed to be irrevocable. Utah state statutes and relevant federal laws will apply to the administration and taxation of irrevocable trusts.