An irrevocable trust created by a married couple to avoid probate and minimize federal estate tax. An AB trust is created by each spouse placing property into a trust and naming someone other than his or her spouse as the final beneficiary of that trust. Upon the death of the first spouse, the surviving spouse does not own the assets in that spouse's trust outright, but has a limited power over the assets in accordance with the terms of the trust. Such powers may include the right to receive interest or income earned by the trust, to use the trust property during his or her lifetime, e.g. to live in a house, and/or to use the trust principal for his or her health, education, or support. Upon the death of the second spouse, the trust passes to the final beneficiary of the trust. For estate tax purposes, the trust is included in the first, but not the second, spouse's estate and therefore, avoids double taxation.