S.D. Codified Laws § 3-13-66

Effective for any year that a participant attains age fifty years or older, or attains the age set forth in § 414(v)(2)(E) of the Internal Revenue Code, the participant may make an additional elective deferral equal to the applicable dollar amount associated with a particular year, pursuant to § 414(v)(2)(B) of the Internal Revenue Code, as indexed after December 31, 2006, pursuant to § 414(v)(2)(C) of the Internal Revenue Code, in addition to the participant's maximum deferral under § 3-13-56.5.