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 Pennsylvania, an irrevocable trust is a type of trust that, once established, cannot be altered, modified, or terminated by the grantor without the consent of the trust's beneficiaries. The creation of an irrevocable trust involves a permanent transfer of ownership of assets from the grantor to the trust, which is managed for the benefit of the beneficiaries. This transfer of ownership can provide certain tax advantages, as the assets are no longer considered part of the grantor's estate for estate tax purposes. Pennsylvania trust law is governed by the Pennsylvania Uniform Trust Act, which outlines the rules and regulations for the creation and administration of trusts within the state. While the default assumption is that trusts are irrevocable unless stated otherwise in the trust document, Pennsylvania law does allow for modifications or terminations of irrevocable trusts under certain circumstances, such as with the consent of all beneficiaries or by court approval if it is deemed that the modification or termination will not defeat the purpose of the trust.