Interest rate warning: How Reserve Bank move could hit homeowners

Analysts warn that a Reserve Bank move could sting mortgage holders by more than regulators think. Photo / 123rf

Mortgage rates could jump up by much more than what the Reserve Bank predicts under proposals to increase the level of capital banks hold, analysts are warning.

That would mean home-owners are paying thousands of dollars more each year in interest payments.

The Reserve Bank earlier this month revealed proposals to nearly double the amount of capital the banks have to have on standby over the next five years in a bid to make the banking system safer.

The central bank's consultation document points to a marginal cost increase for borrowers of around 50 basis points.

That could push up a two-year fixed term interest rate from the current average standard rate of 4.79 per cent to 5.29 per cent.

On a $300,000 mortgage fixed over two years on a 30-year term, it would increase the payments from $1572 per month to $1664.

But Macquarie analysts have predicted the rate rises could be as much as 90 to 140 basis points if the four major Australian-owned banks have to raise an additional A$18 billion (NZ$18.9 billion).

"The RBNZ paper suggests that the pricing response is likely to be immaterial.

"While, theoretically, this may be conceivable, in practice we believe it is highly unlikely.

"We estimate that banks' return on capital in NZ would decline by about 40 per cent, falling from about 17 per cent to about 10 per cent, suggesting that on average NZ returns would fall below the cost of equity.

"We estimate that banks would need to raise their pricing by about 90 to 140bps to offset the reduction in returns."

At the top end of that estimate, the monthly cost of a $300,000 mortgage could rise to $1835 - a jump of $263 a month or several thousand dollars a year.