Low interest rates look likely to remain for some time yet if this week's third quarter consumers price data continues to point to subdued inflation, as economists expect.

Tuesday's release from Statistics NZ is expected to show that inflation ticked up by 0.4 per cent over the September quarter, making for a 1.8 per cent gain, year-on-year.

That's up a touch from the Reserve Bank's own forecasts but still nothing to shake the bank from its current stance, which is to keep the official cash rate (OCR) at a record-low 1.75 per cent.

At 1.8 per cent, the annual rise would take inflation close to the midpoint of the Reserve Bank's mandated 1 to 3 per cent range.


The fact that inflation has remained low for such a long time, both here and around the world, remains a great mystery for economists.

In New Zealand's case, recent history shows that inflation only went outside the Reserve Bank's target band in 2010 and 2011, around the time the Government raised GST to 15 per cent from 12.5 per cent.

Abnormally low inflation is something that has been exercising the minds of central bankers here and the around the world.

"It's not just a local phenomenon," ASB Bank senior economist Mark Smith said.

"Globally, people are scratching their heads, saying why is inflation continuing to stay so low?

"We don't see anything on the horizon that suggests that inflation is going to pick up significantly, and so the Reserve Bank will have the luxury of keeping the official cash rate where it is for quite a long period of time," Smith said.

The Reserve Bank's OCR is just one influence over what happens to interest rates. There are others.

There is straight-out demand for mortgage finance.


Spring is typically a time when a lot of real estate tends to change hands, so demand for mortgages generally heats up, but muted house sales compared with this time last year has meant lower demand, Smith said.

Another influence is wholesale interest rates, which have remained at around 2 to 2.5 per cent over the last 12 months.

There are overseas funding costs, which are largely influenced by the US Federal Reserve.

Expectations are that the Fed will hike rates three times next year, but there remains conjecture as to when or if the bank will move.

Finally, bank funding costs have an impact; six month deposit rates of around 3.5 per cent suggests banks are competing to fund themselves locally.

But for the time being, economists do not expect domestic interest rates to race away.
NZIER senior economist Christina Leung agreed that there was no urgency for the Reserve Bank to start raising rates.

There was potential for upward pressure on mortgage interest rates if there was an escalation in political tension around the world, or if the Fed started hiking rates, Leung said.

"Overall, while we would expect to see potential for interest rates to lift over the coming years, we would expect them to remain low from an historical perspective," she said.

At the Reserve Bank's September review, acting Reserve Bank governor Grant Spencer signalled no change was imminent.

Rates have been on hold since November last year and the central bank's forecasts show it does not expect to lift them until September 2019, at the earliest.

At Tuesday's release, housing and food continue to be the key drivers of inflation, with pressures soft elsewhere.

Rising petrol prices and a stronger near-term outlook for food prices likely explain much of the difference with the Reserve Bank's forecast of a 0.2 per cent quarterly increase.

"We expect the CPI to confirm that domestic inflation pressures remain subdued outside of one or two pockets and while the outlook for economic activity remains constructive and the beneficiary of a number of key supports, evidence of a firming in inflationary pressure is mixed at best, ANZ senior economist Phil Borkin said.

"The hurdle for action remains high, and policy looks set to be on hold for an extended period," Borkin said.