Kansas City, Mo.-based H&R Block Inc., the nation’s largest income tax preparer, said Monday that Chief Operating Officer Jeffrey Yabuki was stepping down to run data processing provider Fiserv Inc.

Yabuki will become the Brookfield, Wis., company’s president, chief executive and a member of the board of directors, replacing Leslie Muma, who is retiring. The change will be on or before Dec. 1.

Fiserv sells data processing equipment and services to the financial industry.

Yabuki started with H&R Block in 1999 and has focused mostly on integrating the company’s income tax work with its burgeoning list of financial and investment services. He also ran the company’s income tax division in 2003 and 2004.

Mark Ernst, H&R Block’s chairman and CEO, said the company was looking for a replacement.