The birth mother may apply for the child’s SSN at the hospital. If she does apply for it, the card will be mailed to the address she discloses on the application. However, she is not compelled to do it and occasionally, she does not. If the birth mother does not apply for it, the adoptive parents will be able to apply for a new SSN for the child after the adoption is granted. In the meantime, they could apply for and receive a temporary number for the child from the IRS for taxes just while the adoption is pending.