20 CFR §404.371

1. (a)You are entitled to parent's benefits beginning with the first month covered by your application in which you meet all the other requirements for entitlement.
2. (b)Your entitlement to benefits ends with the month before the month in which one of the following events first occurs:
   1. (1)You become entitled to an old-age benefit equal to or larger than the parent's benefit.
   2. (2)You marry, unless your marriage is to someone entitled to wife's, husband's, widow's, widower's, mother's, father's, parent's or disabled child's benefits. If you marry a person entitled to these benefits, the marriage does not affect your benefits.
   3. (3)You die.