ASB's cash net profit dropped just 1 per cent or $6 million to $614 million for the six months to December 31.
The bank's operating income rose 1 per cent to $1.404 billion while its expenses were up 3 per cent to $521m.
ASB chief executive Vittoria Shortt said the result reflected the continued resilience of the New Zealand economy in the face of the ongoing impacts of Covid-19.
ASB saw a big boost in its home loan business the value of which rose 9 per cent to $64.45b.
Business lending was up 3 per cent to $18.1b while rural lending was flat at $11b.
Deposits rose 6 per cent to $63.64b.
The bank's net interest margin fell 6 basis points from a year earlier to 2.09 per cent but was flat compared to the June half year.
The biggest percentage rise was in its loan impairment expense which rose from $22m to $30m comparing the December 2020 half to the December 2019 half year bringing the total provision to $604m.
Arrears for both its home loans and consumer finance ticked up over the year. Home loan arrears past due by more than 90 days rose from 0.14 per cent to 0.18 per cent.
For consumer loans arrears past 90 days rose from 0.59 per cent to 0.74 per cent.
Shortt said the bank remained confident about New Zealand's ability to remain resilient to the challenges of Covid-19, but the past 12 months had taught it to expect the unexpected.
"That is why we have made a conscious decision to continue to provision for the uncertainties surrounding the pandemic and its possible long-term effects."
The number of full time equivalent staff rose 6 per cent from 5,074 to 5,381.
No mortgagee sales for owner-occupiers
Shortt said banks played an important role in the financial wellbeing of New Zealanders and it knew the year ahead would be difficult for some.
"That is why ASB is making a commitment today to keep Kiwi families in their homes."
Shortt said there would be no forced sales of owner-occupied family homes in 2021 for ASB customers.
"Mortgagee sales are uncommon, and they are always the last resort, however, we are taking this step to give customers added peace of mind during what is a very worrying time for some."
ASB parent Commonwealth Bank of Australia saw its net profit after tax fall 21 per cent from A$6.16b ($6.5b) to A$4.88b for the six months to December 31.
Its cash profit was A$3.89b down 11 per cent from A$4.36b.
It will pay a dividend of A$1.50 per share.
CBA chief executive Matt Comyn said although the outlook was positive there were a number of health and economic risks that could dampen the pace of recovery.
"We are prepared for a range of scenarios and have taken a careful approach to provisioning. We also continue to monitor our lending portfolios closely for any signs of stress."
Comyn said the low interest rate environment would continue to put pressure on its revenue which is why the bank remained focused on its performance, operational execution and capital allocation.
"The strength of our balance sheet and capital position enables us to support customers and held lead the country through recovery. We will also continue to work with government, regulators and our industry peers to support initiatives that stimulate economic activity and jobs."