Kerstan was born in Saskatchewan and grew up on the family farm. He graduated from the University of Saskatchewan in 2000 with a Bachelor of Science degree and in 2002 with a Bachelor of Commerce degree. Kerstan began working in Red Deer in 2002, received his Chartered Accountant designation in 2005 and later became a Chartered Professional Accountant in 2016. After joining the firm in 2007, Kerstan became a partner in 2010.
Kerstan volunteered with Habitat for Humanity from 2007 to 2013, serving as treasurer from 2008 to 2013. He is active in Home Church and became a director of the board in 2014. He is married to Christi, and together they raise three amazing children. Kerstan focuses his practice on the agriculture industry, helping clients setting up new businesses or those operating small to medium sized businesses.