An adjustable seat cushion assembly is disclosed which exhibits a first seat element and a second seat element moveable relative to the first seat element. A cover piece straddles a variable gap between cushion parts of the first and second seat elements. The adjustable seat cushion assembly is configured to draw the cover piece into the gap when the seat cushion assembly is moved from an extended position into a retracted position. A hem is formed with the cover piece in an area between the two cushion parts, and is joined with the second seat element. A link rod extends in the seat width direction of the cover piece and engages into slots at opposite ends.