From July 1 the insurer will take more account of risk in its premiums and roll out changes to all its brands as well as the insurance its sells through bank ASB, BNZ, The Co-Operative Bank and Westpac.
Last year it changed the premiums for its AMI and State Insurance customers to take into account risk from earthquakes and floods, with some areas seeing an average premium increase of $91 and others an average cut of $54.
But now the insurer plans to roll out its risk-based pricing across the board for all its home and contents policies. This follows a similar move by Tower Insurance in April 2018.
Kevin Hughes, executive general manager customers and consumer at IAG, said the change was being made because it needed to "reflect the level of risk and costs associated with providing insurance cover, including reinsurance costs."
"Every customer and every property is different and so every policy will be affected differently, whether that be a price increase or decrease.
Hughes said New Zealand's environmental risks had evolved over the past few years.
"We need to take more account of those risks, so we can continue to be there for our customers across New Zealand when misfortune strikes."
Hughes said it realised the changes would be a challenge for some customers.
"We will work through this with them.
"There are a range of options available to customers to make this easier, including taking a higher excess or adjusting the frequency of payments to suit them.
"We will continue to provide solutions and work to make insurance as affordable as possible."
The insurance giant came under fire last month over its moves in Wellington, with some claiming it had pulled out of the market.
IAG said it was still operating in Wellington but had changed its focus to servicing existing customers rather than new customers.
Hughes said last month it had taken a prudent approach to insurance in Wellington in the wake of the Kaikoura quakes but as part of an ongoing review process, IAG had decided to review its position regarding both new and existing customers.
"The feedback from our existing customers is they want us to be there for them," he said.
"As such our focus has been to broaden our support and to protect existing customers. This includes making sure insurance is available as the circumstances of our customers change. For example, when an existing customer buys a new home, we want to ensure we are able to provide insurance coverage for their new property and that we're there for them if they need to make a claim," he added.
IAG has around 46 percent of the New Zealand general insurance market.
The IAG changes come at the same time as the Earthquake Commission is changing its cover.
From 1 July, EQC will pay up to $150,000 plus GST per residential home but will no longer provide cover for contents. Contents insurance cover will fall entirely to private insurers.
