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 Delaware, an irrevocable trust is a type of trust that, once established, cannot be altered, amended, or terminated by the creator of the trust, 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. This transfer is considered permanent, and it effectively removes the assets from the grantor's taxable estate, potentially resulting in significant tax advantages. Delaware law requires that the terms of the trust must clearly indicate whether a trust is revocable or irrevocable. If the trust document does not specify, the trust is generally presumed to be irrevocable. Delaware is known for its favorable trust laws, including privacy protections and the ability to create a 'Dynasty Trust,' which can last in perpetuity, far beyond the time limits imposed by other states. It is important for individuals creating an irrevocable trust in Delaware to work with an attorney to ensure that the trust is structured properly to meet their estate planning goals and to comply with both state and federal laws.