Exhibit 21 SUBSIDIARIES OF CASS INFORMATION SYSTEMS, INC.* Name & Address State of Incorporation - -------------- ---------------------- Cass Commercial Bank Missouri 13001 Hollenberg Drive Bridgeton, Missouri 63044 Cass Information Systems, Inc. Missouri 13001 Hollenberg Drive Bridgeton, Missouri 63044 *Pursuant to Item 601(b) (21) (ii), the names of particular subsidiaries may be omitted if the unnamed subsidiaries, considered in the aggregate as a single subsidiary, would not constitute a significant subsidiary (as such term is defined in Rule 1-02 (W) of Regulation S-X) as of the end of the year covered by this annual report on Form 10-K.