31 CFR §240.16

1. (a)Checks in payment of principal and/or interest on U.S. securities that are issued to minors may be indorsed by:
   1. (1)Either parent with whom the minor resides; or
   2. (2)If the minor does not reside with either parent, by the person who furnishes the minor's chief support.
2. (b)The parent or other person indorsing on behalf of the minor must present with the check the indorser's signed statement giving the minor's age, and stating that the payee either resides with the parent or receives his or her chief support from the person indorsing on the minor's behalf and that the proceeds of the check will be used for the minor's benefit.