20 CFR §408.320

1. (a)A person who signs an application for you will be required to give us evidence of his or her authority to sign the application for you under the following rules:
   1. (1)If the person who signs is a court-appointed representative, he or she must give us a certificate issued by the court showing authority to act for you.
   2. (2)If the person who signs is not a court-appointed representative, he or she must give us a statement describing his or her relationship to you. The statement must also describe the extent to which the person is responsible for your care.
   3. (3)If the person who signs is the manager or principal officer of an institution which is responsible for your care, he or she must give us a statement indicating the person's position of responsibility at the institution.
2. (b)We may, at any time, require additional evidence to establish the authority of a person to sign an application for you.