Maxus is the incumbent on the offline media planning and buying business, while a roster of digital agencies including Harvest look after online planning and buying.
It is understood that Experian's procurement department is leading the process and that the company is looking to consolidate its media business into one agency.
Experian has drawn up a shortlist to pitch for the business and Maxus is expected to repitch.
Maxus won the account from Media Campaign Services in February 2010.
It is understood that the review is tied to an increase in advertising spend ahead of an update of Experian's consumer products.
CreditExpert's most recent TV campaign, through The Red Brick Road, broke in February. The creative business is not under review.