20 CFR § 404.987 - Reopening and revising determinations and decisions.
(a) General. Generally, if you are dissatisfied with a determination or decision made in the administrative review process, but do not request further review within the stated time period, you lose your right to further review and that determination or decision becomes final. However, a determination or a decision made in your case which is otherwise final and binding may be reopened and revised by us.
(b) Procedure for reopening and revision. We may reopen a final determination or decision on our own initiative, or you may ask that a final determination or a decision to which you were a party be reopened. In either instance, if we reopen the determination or decision, we may revise that determination or decision. The conditions under which we may reopen a previous determination or decision, either on our own initiative or at your request, are explained in § 404.988.