Marga started her career as an Assistant Accountant at Deloitte Amsterdam in 1986. 

In 1991 she moved to Intertrust, a large service provider were she was responsible for all financial services of the client portfolio. She later joined Intruad Management B.V., in 1997 - a small service provider, where she later become an owner in 2011. In April 2018, Intruad Management B.V. joined Ocorian, whereby Marga become an Executive Director.