Revocable trusts allow trustees to have access to all your assets. An irrevocable trust may interfere with your right to control the trust, but you get to decide as to what extent that will be. 

     After a trust is created, it is still subject to change. This however would not apply to an irrevocable trust created for the purpose of avoiding taxes. Other trusts can be changed depending on the language used. Keep in mind that when you create a trust you must give up your right to something to some degree. 

     Certain laws provide that whatever can be had by you, can be had by creditors. These creditors can be known or unknown  and a typical “income only” irrevocable trust allows you to receive income on your assets. If you do this then you will have to give up your rights to the principal. Some irrevocable trusts allow you to change who gets your assets during your life and after death. If you choose to do so, you can maintain 100% of your assets until mental disability or death.

     Tax reduction trusts are typically much more restrictive than asset protection trusts. Usually you cannot keep rights to control or access any assets in an irrevocable tax reduction/avoidance trust. Many irrevocable trusts are available that are quite flexible and grantor-friendly. Consult a qualified estate attorney to get counseled on all options before creating an irrevocable trust.