26 U.S. Code § 2516. Certain property settlements
Where a husband and wife enter into a written agreement relative to their marital and property rights and divorce occurs within the 3-year period beginning on the date 1 year before such agreement is entered into (whether or not such agreement is approved by the divorce decree), any transfers of property or interests in property made pursuant to such agreement—
to either spouse in settlement of his or her marital or property rights, or
shall be deemed to be transfers made for a full and adequate consideration in money or money’s worth.