But the wider group experienced a profit drop from $A758 million to $A693 million, although gross written premiums rose from $A4.7 billion to A$5.6 billion.
That wider result came from all operations in Australia, New Zealand, Thailand and Vietnam where IAG employs more than 15,000 people.
While many Canterbury people are still struggling to get resolution on their insurance claims, IAG indicated its New Zealand returns were robust.
"New Zealand has continued to register a strong underlying performance, while the reported margin of 19.2 per cent was enhanced by a particularly benign natural perils experience. The business has maintained its market-leading position, with gross written premium growth of 26.2 per cent centred on the acquired Wesfarmers business.
"Modest like-for-like growth in personal lines was countered by some volume loss as a result of tougher commercial market conditions," it said.
IAG has the State, NZI, AMI and Lumley Insurance brands here and noted the integration of Lumley Insurance business progressing to plan.
IAG said there had been solid progress on the Canterbury rebuild, with an increase in expected gross claim costs, but within reinsurance cover.
"New Zealand's 1H15 gross written premium of $1.2 billion increased by 22.2 per cent compared to the same period last year. This strong growth reflects the first six months' contribution from Lumley Insurance following its acquisition as part of the Wesfarmers transaction."
On the Canterbury rebuild, IAG said it had advised in December that there has been a significant increase in the expected final claim cost arising from the earthquakes.
"This follows an increase in forecast repair and rebuild costs; the continued notification of new household claims that have exceeded the Earthquake Commission's (EQC) $100,000 residential dwelling limit; and a series of adverse court judgements which have affected the insurance industry over the past six months.
"Of the $950 million increase recognised, the majority relates to the 22 February 2011 event. Gross claim reserves for this event now stand close to the applicable reinsurance limit of $4 billion Loss estimates for the other major earthquake events are expected to settle well below respective reinsurance limits.
"At 31 December 2014 the New Zealand business had completed over $3.9 billion in claim settlements in respect of the Canterbury earthquakes (FY14: over $3.3 billion). Approximately 69 per cent (FY14: 58 per cent) of all claims by number had been fully settled at that date," IAG said in a section on New Zealand.