Mortgage Stress Test in NZ: Why Banks Use ~7% (and What It Means for You)
Banks do not assess your loan at the headline interest rate. Here is how the stress test works, why it exists, and how to plan around it.
If you have ever used an online calculator at 6% and then heard a much lower number from the bank, you have already met the mortgage stress test. Lenders check whether you could still afford repayments if rates were materially higher than today’s offers. In practice, that test rate is often around 7% (banks adjust over time — always confirm current policy with your adviser).
Stress test vs the rate you pay
- Actual rate — what you are quoted for a fixed or floating loan today.
- Test rate — the higher rate used to calculate whether repayments fit your budget after tax, living costs, and other commitments.
Your borrowing power is therefore lower than a simple “6% mortgage calculator” suggests. That gap is not the banker being difficult — it is RBNZ and lender prudential standards doing their job.
Why regulators care
Households in NZ carry a lot of floating or short-fixed debt. When the OCR moves, repayments can jump at refix. The stress test is a buffer so borrowers do not commit every spare dollar at today’s rate and then hit distress when rates normalise or spike.
What you should do with this information
- Model at the test rate before you fall in love with a listing.
- Use surplus as your safety margin — not “we can technically make the payment.”
- Explore rate scenarios — MortgageReady’s Rate Sensitivity Explorer shows how surplus moves between roughly 4% and 10%.
Related concepts
Stress testing interacts with DTI, LVR, and serviceability. Our glossary ties them together; for a deeper read, see why borrowing power is lower than you think and interest rate moves and your buffer.
Create a free profile, see your scenarios at the stress-test settings MortgageReady uses, and download a free summary PDF before your first lender conversation.