New York Laws
Part 6 - Uniform Transfers to Minors Act
7-6.20 - Termination of Custodianship

(a) the minor's attainment of twenty-one years of age with respect to
custodial property transferred under 7-6.4 or 7-6.5;
(b) the minor's attainment of age eighteen or other statutory age of
majority of New York with respect to custodial property transferred
under 7-6.6 or 7-6.7; or
(c) the minor's death.