Addison provides software applications for tax advisers, CPAs, and medium-sized companies. It generated E48m ($68.2m) revenue in fiscal 2007 and has over 340 employees.

This is the third acquisition by Wolters Kluwer this year. Earlier this month, it acquired electronic clinical information company UpToDate to strengthen its health portfolio. In March, it acquired the accountants division of MYOB UK and MYOB Ireland to expand its presence in the UK market.