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 South Dakota, an irrevocable trust is a type of trust that, once established, cannot be altered, 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 primary 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 complete and permanent, which can provide certain tax advantages, as the assets are no longer considered part of the grantor's estate for tax purposes. South Dakota law generally presumes a trust to be irrevocable unless the trust instrument explicitly states otherwise. The state's trust laws are designed to be flexible and favorable for trust creation and administration, making it a popular jurisdiction for trust formation. It is important for individuals considering setting up an irrevocable trust in South Dakota to consult with an attorney to understand the specific implications and ensure that the trust is structured in accordance with state law and their estate planning goals.