Money · Credit · New Zealand · Part 25
Why does the Reserve Bank target inflation instead of house prices?
Because stabilising the general price level and preventing dangerous housing-credit cycles are related problems, but they require different tests and different tools.
Housing is one of the most politically charged parts of the New Zealand economy.
When house prices rise quickly, people ask why the Reserve Bank does not simply stop them.
When the OCR rises and mortgage payments increase, people ask why borrowers are being squeezed while the price of a house is not even part of the inflation target in the same way as groceries, electricity or petrol.
Those are fair questions.
But they combine two different policy objectives.
Monetary policy: stabilise the general level of prices over the medium term.
Financial stability policy: reduce the risk that lending and asset-price cycles damage households, banks and the financial system.
House prices matter to the Reserve Bank. They are simply not the same thing as the inflation rate the Monetary Policy Committee is legally required to stabilise.
The legal objective comes first
Section 9 of the Reserve Bank of New Zealand Act 2021 gives the Bank an economic objective of:
“achieving and maintaining stability in the general level of prices over the medium term”.
The Act separately gives the Bank a financial-stability objective of protecting and promoting the stability of New Zealand's financial system.
New Zealand Legislation — Reserve Bank of New Zealand Act 2021, section 9 ↗
The Monetary Policy Committee's current operational objective translates the price-stability mandate into a target:
future annual inflation between 1% and 3% over the medium term, with a focus on keeping future inflation near the 2% midpoint.
Reserve Bank — Monetary Policy Handbook ↗
Inflation is currently above that range
Annual CPI inflation was 4.1% in the June 2026 quarter.
Stats NZ — Annual inflation at 4.1 percent in June 2026 ↗
The OCR is currently 2.50%, and the Reserve Bank says it will adjust interest rates to return inflation to the 2% midpoint over the medium term.
Reserve Bank — The Official Cash Rate ↗
At the same time, the Reserve Bank said in August 2026 that national house prices had remained broadly flat in recent years and that housing-related financial-stability risks were currently contained.
Reserve Bank — LVR settings maintained, August 2026 ↗
That contrast is useful.
Consumer-price inflation can be too high while house prices are flat.
Or house prices can rise rapidly while consumer-price inflation remains relatively contained.
They are related, but they are not the same variable.
What does the CPI actually measure?
Stats NZ defines the Consumers Price Index as a measure of how the prices of goods and services purchased by New Zealand households change over time.
Stats NZ — Consumers Price Index, June 2026 quarter ↗
It is designed to measure changes in the cost of a basket of household consumption and acquisition items.
That includes things such as:
food,
rent,
electricity,
transport,
clothing,
services,
local authority rates,
and the cost of purchasing newly built owner-occupied dwellings excluding land.
But it does not simply insert the market price of every existing house into the CPI.
Why is the market price of an existing house different?
Because a house is both a place to live and a long-lived asset.
If one household buys an existing house from another household for $900,000, New Zealand has not consumed a $900,000 good that disappears after use.
Ownership of an existing asset has changed.
The price can still matter enormously for:
wealth,
borrowing,
financial stability,
housing affordability,
and future spending.
But that is conceptually different from a broad increase in the current prices of goods and services being consumed across the economy.
A rising asset price can make households richer or poorer relative to one another without being the same thing as a general rise in consumer prices.
The CPI does include some housing costs
This point is often lost.
Housing is not absent from the CPI.
Stats NZ's current approach includes the cost of purchasing new dwellings excluding land rather than using market house prices as the owner-occupied housing measure.
Rents and a range of housing-related goods and services are also included.
Stats NZ — Treatment of owner-occupied housing ↗
So saying “housing is not in inflation” is too crude.
The more accurate statement is:
market house prices and mortgage interest are not treated as the CPI measure of owner-occupied housing costs.
Why is mortgage interest not in the CPI?
Stats NZ gives a very practical reason.
The Reserve Bank uses the CPI to help set the OCR.
If mortgage interest were included directly in that same CPI measure, an OCR increase could mechanically raise measured inflation through higher mortgage-interest costs.
That creates circularity:
the Reserve Bank raises rates to reduce inflation,
higher rates directly raise the inflation index,
which could then appear to require still higher rates.
Stats NZ therefore excludes interest from the CPI and uses a different treatment for owner-occupied housing.
Stats NZ — CPI and Household Living-costs Price Indexes ↗
For households wanting a measure closer to their own lived costs, Stats NZ publishes Household Living-costs Price Indexes, which do include interest payments and use a market-value property-price link for owner-occupied housing.
The CPI is not intended to reproduce every household's personal cost-of-living experience. It is a macroeconomic price index built for a different purpose.
So why does the Reserve Bank care about house prices at all?
Because house prices can affect both monetary policy and financial stability.
The Reserve Bank identifies several channels.
Higher house prices can increase household wealth and confidence.
They can support more consumption.
They often occur alongside stronger mortgage lending.
And if borrowers take on very large debts relative to income or property value, a later house-price correction can create financial stress.
Reserve Bank — How house prices affect the economy ↗
So house prices enter monetary-policy analysis as part of the transmission mechanism and economic outlook.
They are not ignored.
But targeting house prices with the OCR would create a major problem
Imagine consumer inflation is weak, unemployment is high and the economy is in recession.
But house prices in Auckland are rising rapidly.
If the Reserve Bank raised the OCR solely to suppress Auckland house prices, it would tighten borrowing conditions for:
businesses in Invercargill,
farmers in Waikato,
first-home buyers in Christchurch,
manufacturers in Tauranga,
and households across the country.
The OCR is a national price of short-term money.
It is an extremely broad tool.
Using a national interest rate to target one asset market can impose costs on parts of the economy that have nothing to do with the original problem.
The reverse problem exists too
Imagine house prices are falling but consumer-price inflation is 6% and broad demand is overheating.
If the Reserve Bank cut interest rates merely to support house prices, it could make general inflation worse.
This is why the Bank needs separate policy frameworks for separate risks.
That is where macroprudential policy enters
Macroprudential tools are designed to reduce risks building inside the financial system.
They do not attempt to select the “correct” dollar price for a house.
Instead they ask:
how leveraged are borrowers?
how much equity do they have?
how exposed are banks to a housing correction?
and how much high-risk lending is entering the system?
The Reserve Bank currently uses both loan-to-value ratio restrictions and debt-to-income restrictions for residential mortgage lending.
LVR rules target equity risk
Loan-to-value ratio restrictions limit how much high-LVR mortgage lending banks can make.
The August 2026 settings allow:
up to 25% of new owner-occupier lending to have an LVR above 80%,
and
up to 10% of new investor lending to have an LVR above 70%.
Reserve Bank — Current LVR settings ↗
These are portfolio speed limits.
They do not mean every borrower must have exactly a 20% or 30% deposit.
Banks are allowed a specified share of lending above the thresholds and still apply their own credit criteria.
DTI rules target income leverage
Debt-to-income restrictions focus on a different risk.
They compare a borrower's total debt with annual gross income.
The current rules allow banks to make:
up to 20% of owner-occupier lending to borrowers with DTI ratios above 6,
and
up to 20% of investor lending to borrowers with DTI ratios above 7.
Reserve Bank — Understanding DTI restrictions ↗
The Reserve Bank describes DTIs as a guardrail designed to become more binding when low interest rates and strong housing demand encourage highly leveraged borrowing.
Reserve Bank — Macroprudential Policy Framework ↗
LVR and DTI restrictions do not target a house-price level
This distinction matters.
The Reserve Bank does not announce:
“The median house price should be $650,000.”
Instead it tries to make the banking system and borrowers more resilient if prices rise rapidly and later correct.
A housing market can therefore remain expensive while financial-stability risks are judged contained.
That may be deeply frustrating from an affordability perspective.
But affordability and financial stability are not identical objectives.
Housing affordability involves much more than monetary policy
House prices reflect interaction between:
land supply,
planning rules,
infrastructure capacity,
construction costs,
population growth,
household income,
tax settings,
credit availability,
interest rates,
investor expectations,
and the existing housing stock.
The Reserve Bank influences some of those factors through financial conditions.
It does not control most of them.
This is why asking the central bank to solve housing affordability on its own gives one institution responsibility for a problem created across many systems.
The mandate nevertheless requires house prices to be considered
The Reserve Bank says that, following changes made in 2023, house-price sustainability is addressed through the Monetary Policy Committee Charter rather than being a separate monetary-policy objective in the Remit.
The Charter requires the MPC to explain its assessment of how monetary policy affects the Government's objective of supporting more sustainable house prices.
Reserve Bank — House prices and the monetary-policy mandate ↗
That is an important middle position.
The Bank must consider the housing effects of monetary policy.
But those effects do not replace its statutory price-stability objective.
What if house prices rise because interest rates fall?
Then monetary policy may be part of the explanation.
Lower mortgage rates increase borrowing capacity.
That can increase demand for housing and support prices.
But the same interest-rate cut may also be needed because consumer inflation is below target and the wider economy is weak.
This is precisely why DTI guardrails are useful.
The Reserve Bank's macroprudential framework says DTIs can constrain the build-up of highly leveraged lending during low-rate housing booms without requiring the OCR itself to carry the entire financial-stability burden.
There is still no perfect separation
Monetary policy affects financial stability.
Financial-stability rules affect credit conditions.
Housing affects consumption and inflation.
Interest rates affect housing.
The tools overlap.
But overlap does not mean the objectives should be collapsed into one number.
Why does this distinction matter for the rest of this series?
Because the same principle applies to public investment and credit allocation.
We should not ask one blunt instrument to solve every economic problem.
The OCR is designed to influence economy-wide inflation.
LVR and DTI rules are designed to limit housing-related financial risk.
Planning policy can increase land and development capacity.
Infrastructure policy can unlock housing supply.
Tax policy can change investment incentives.
Bank regulation can change the risk profile of credit.
Those tools should be coordinated.
They should not be confused.
A useful policy map
I would separate the system this way.
CPI inflation too high or too low → monetary policy.
Too much highly leveraged mortgage lending → macroprudential tools such as DTI and LVR restrictions.
Insufficient housing supply → planning, infrastructure, construction capacity and land-use policy.
Housing affordability → income, supply, financing, tax and social-policy settings.
Bank solvency and resilience → prudential capital, liquidity and supervision.
Speculative or poorly allocated credit → a broader combination of regulation, taxation, underwriting standards and market incentives.
A good policy framework starts by identifying the problem correctly before choosing the tool.
My conclusion
The Reserve Bank targets inflation rather than house prices because its monetary-policy mandate is to maintain stability in the general level of prices.
House prices matter, but they are asset prices with important effects on wealth, borrowing and financial stability.
Trying to force the OCR to deliver both a specific house-price outcome and economy-wide price stability could create serious conflicts.
So New Zealand uses different tools.
The OCR influences general financial conditions and inflation.
LVR and DTI rules limit risky mortgage lending.
And housing affordability itself requires policy well beyond the central bank.
The Reserve Bank should care about house prices without pretending the OCR can solve the housing market.
Next
That brings us to the next credit question:
If housing absorbs so much bank lending, does that starve productive businesses of capital?
Part 26 will examine whether mortgage lending actually crowds out business lending, how bank capital and collateral affect allocation, why housing security is attractive to lenders, and what would have to change if New Zealand wanted more credit flowing toward productive investment.
Primary sources
Reserve Bank of New Zealand Act 2021 — section 9 ↗
Reserve Bank — Monetary Policy Handbook ↗
Stats NZ — Consumers Price Index, June 2026 quarter ↗
Stats NZ — CPI and Household Living-costs Price Index methodology ↗
Reserve Bank — How House Prices Affect the Economy ↗