The company, which owns brands that include Hastings Direct, Equity Redstar and Equity Insurance Brokers, currently uses Story to produce its DM. The agency will repitch for the business.
The winner will create DM campaigns and some digital communications across all of IAG's UK brands.
The company owns a range of products, from motor vehicle, household and personal accident insurance to roadside rescue and fleet services.
IAG, which was focused on the Australian, New Zealand and Asian markets, expanded into the UK by acquiring Hastings Insurance Services for £140 million in September 2006. The company went on to buy Advantage Insurance and Equity Insurance Group shortly after.
Claire Day, IAG's marketing director, will be handling the review.