of such property or investment. (4) One election per property No election may be made under paragraph (1) with respect to a sale or exchange if an election previously made with respect to such sale or exchange is in effect. (b) Basis rules relating to qualified opportunity zone property (1) Reduced by gain deferred under subsection (a)(1) The basis of a qualified opportunity zone property immediately after its acquisition under subsection (a) shall be reduced by the amount of gain deferred by reason of subsection (a)(1)(A) with respect to such property. (2) Increase for gain recognized under subsection (a)(2) The basis of qualified opportunity zone property shall be increased by the amount of gain recognized by reason of subsection (a)(2) with respect to such property. (3) Subsequent increase in basis for property held for at least 5 years but less than 10 years In the case of qualified opportunity zone property held for at least 5 years but less than 10 years— (A) Property held for 5 years For qualified opportunity zone property held for at least 5 years, the basis of such property shall be increased by an amount equal to 10 percent of the amount of gain deferred by reason of subsection (a)(1)(A) with respect to such property. (B) Property held for 7 years For qualified opportunity zone property held for at least 7 years, the basis of such property shall be increased by an amount equal to 5 percent of the amount of gain deferred by reason of subsection (a)(1)(A) with respect to such property. (c) Qualified opportunity zone property For purposes of this section: (1) In general The term qualified opportunity zone property means property which is— (A) qualified opportunity zone stock, (B) qualified opportunity zone partnership interest, (C) qualified opportunity zone business property, or (D) an interest in a qualified investment fund. (2) Qualified opportunity zone stock (A) In general Except as provided in subparagraph (B), the term qualified opportunity zone stock means any stock in a domestic corporation if—