On the other hand, an irrevocable trust cannot be altered by the grantor after it has been executed. This characteristic can be very helpful. Once an irrevocable trust has been created, the trust assets are in effect out of the reach of creditors and the probate court. They are not subject to estate taxes either. Although you relinquish control over your assets when they are placed in an irrevocable trust, you gain favorable tax consequences. An irrevocable trust is commonly preferred over a revocable trust if the goal is to reduce estate taxes.