What debt-to-income (DTI) means
DTI compares total debt with gross annual income. The Reserve Bank of New Zealand (RBNZ) uses DTI restrictions as a bank-level safeguard on new residential mortgage lending—not as a promise that an individual can borrow a particular amount.
Current RBNZ thresholds
For registered-bank lending, the high-DTI thresholds are above 6 times gross income for owner-occupiers and above 7 times for investors. Banks may still make a limited share of lending above those thresholds: the current speed limits allow up to 20% of new lending in each category to be high-DTI. This is a portfolio limit for banks, not an entitlement for an applicant.
A result below a threshold does not guarantee approval. A result above it does not automatically mean every application will be declined. The lender makes an individual decision under its own policies and the rules that apply to the loan.
An illustrative owner-occupier calculation
Suppose gross household income is $120,000 a year and existing debt is $20,000:
- Six times gross income: $120,000 × 6 = $720,000 total debt
- Less existing debt: $720,000 − $20,000 = $700,000 illustrative mortgage at the threshold
- Which debts and credit facilities will you include in my DTI calculation?
- How will you assess my income, regular expenses, and repayment buffer?
- Which deposit, LVR, fees, and property-specific requirements apply?
- What current information or documents do you need before assessing my situation?
- RBNZ: Understanding debt-to-income restrictions
- Consumer Protection: What lenders must do
This is only an arithmetic screen. It is not a borrowing estimate, approval, or maximum purchase price. The lender’s DTI calculation and assessment of the whole application control.
DTI is not an affordability test
DTI compares debt with income. A lender separately assesses whether the loan is suitable and affordable, including income, expenses, repayments, and other relevant debts. Deposit size and loan-to-value ratio (LVR) rules are separate considerations. A planning calculation cannot reproduce a lender’s full assessment.
Questions to take to a lender
Use actual figures and current lender information. Don’t close a credit facility, take on new work, or change a deposit plan based only on an online example; consider your own needs and confirm the effect with the relevant provider.
Try a planning scenario
Use the FHBG calculator to explore an illustrative repayment scenario. It is a planning tool, not a lender decision or financial advice.
Sources
*Checked 16 October 2026. Rules and lender policies can change; verify current requirements with RBNZ and the lender assessing your application.*