Revocable living trust provisions can always be changed so long as you have the legal mental capacity to do so. You can change, amend, add to, or revoke your living trust so long as you are alive and well. The same goes for your will, financial power of attorney, health care power of attorney, HIPAA release, living will, and organ donation authorization. You can change them anytime, so long as you are alive and well.
On the other hand, if your trust is irrevocable, it cant be changed.
Of course, there are exceptions. In 2011, most irrevocable trusts are drafted with trust protector provisions so than an independent individual can change the trust terms, without court supervision, to keep the trust in line with the trust makers original intent.
In addition, if there are no trust protector provisions in the trust, or they dont apply, often a new trust, with new terms, can buy the assets of an older trust, with unfavorable terms. Thus, the trust terms are changed.
These planning opportunities make an irrevocable trust, essentially revocable. However, its important that the trust maker maintain no more control than described herein because control means that the trust assets will be drawn back into the estate and subject to federal estate tax.
Avoiding or minimizing the federal estate tax is likely the prominent reason the trust maker created the irrevocable trusts in the first place. In 2011 and 2012, if assets exceed the federal estate tax exemption, about 35% of them are taken by the tax. In 2013, if assets exceed the federal estate tax exemption, about 55%-60% of the assets are taken by the tax.
If you wish to change trust provisions, consult with a qualified estate planning attorney to make sure that any changes are legally valid and dont have negative federal estate tax consequences.