Insurance Australia Group (IAG) says claims from recent floods and bushfires on Australia's east coast could cost it up to $175 million.
More than 13,700 claims related to the impact of ex-tropical cyclone Oswald had been received by the company to date, IAG said on Monday.
The cost to IAG, which operates the NRMA Insurance and CGU businesses, is expected to be in the range of $120 million to $140 million.
A further 600 claims have been lodged after bushfires in NSW, Victoria and Tasmania, with a cost of about $35 million, it said.
IAG's reinsurance program for calendar year 2013 limits the impact of a single natural disaster event to $15 million.