The company has contacted a number of agencies with a request for information and chemistry meetings are due to take place later this month.
A shortlist of agencies will then be drawn up to pitch for the business, with a decision expected towards the end of October.
Aviva currently works with a number of agencies on its UK DM business, including The Gate, Stephens Francis Whitson, Proximity London and Balloon Dog.
Agencies have shared activity for Aviva's investment arm on a project basis. The company recently launched a campaign, created by The Gate, to help promote its investment activity to both businesses and consumers.
Aviva's investment arm is one of the UK's leading providers of investment solutions, offering businesses a range of options such as Investment ISAs and bonds.
The division has more than 1,000 employees, working across 21 locations around the world.
Aviva's current above-the-line agency is Abbott Mead Vickers BBDO, and its digital business is split between glue London, Chemistry, Soup and GT.
The most recent ad campaign for the brand featured the comedian Paul Whitehouse, who takes on various humorous guises, including a Plymouth Argyle football fan and a Welsh Goth, to explain the benefits Aviva insurance.