A corner form apparatus having a rigid, angled form with a pair of leg sections and a plurality of gussets extending between the leg sections. A post is mounted for axial sliding back-and-forth movement within openings formed in the gussets between a pour position and a stripped position. A linear actuator is mounted between the rigid, angled form and the post and a pair of extension mounting arms are pivotally attached to the post at a first end and pivotally attached to each to an associated form extension using slotted holes at a second end whereupon movement of the post between the pour position and the stripping position moves each of the form extensions from a position coplanar with a corresponding one of the rigid, angled form leg sections in the pour position inwardly to a stripped position.