In the first mortgage rate cut of 2011, government owned Kiwibank has dropped its one-year mortgage rate to 6.15 per cent from 6.45 per cent in what it describes as a "limited time offer" likely to run until the end of January.

The cut means Kiwibank now advertises the lowest one year rate from any bank, with HSBC the next lowest with its premier rate at 6.24 per cent. ANZ, National Bank, ASB, BNZ and Westpac all advertise one-year rates of 6.45 per cent.

Kiwibank's move is the second change to mortgage rates by a bank in 2011 following HSBC lifting its one-year premier rate to 6.24 per cent from 5.99 per cent and its six month premier rate to 5.74 per cent from 5.49 per cent.

Under the terms of HSBC's premier offering, customers' must have mortgages worth NZ$500,000 or savings of NZ$100,000 to qualify for a loan.

Kiwibank spokesman Bruce Thompson said the 30 basis point cut to the bank's one-year home loan rate was being promoted as a special - meaning it would only be in place for a limited time.

Thompson said the New Zealand Post subsidiary was aiming to "kick-start the New Year with a very attractive mortgage rate." The new one-year rate matches Kiwibank's floating rate and is available to both new buyers and customers wanting to refinance existing loans.

"It has been some time since there has been any significant changes to interest rates, so Kiwibank is testing the market with a cut-rate one year offer," Thompson said. "We anticipate holding the rate until the end of the month."