Last updated: July 2026
What's My
DTI Ratio?
Enter your household income and debts to check where you sit against the Reserve Bank's debt-to-income restrictions before you apply.
What Is DTI?
Total debt ÷ gross income
DTI is your total debt — including the new mortgage — divided by your gross annual household income.
Reserve Bank speed limits
Banks can only write a limited share of new lending above DTI 6 (owner-occupiers) or DTI 7 (investors) each month.
New builds are exempt
Genuine new-build purchases sit outside the DTI restriction entirely, regardless of ratio.
Exemption headroom varies
Each bank has its own monthly quota for above-cap lending — some months one lender has room when another doesn't.
Close to the DTI Cap?
Finch tracks which lenders still have DTI exemption headroom this month — so a ratio that gets declined at one bank can still get approved at another.
Get Pre-Approved Free →How the NZ Debt-to-Income (DTI) Cap Works
Since 1 July 2024 the Reserve Bank of New Zealand has restricted how much of each bank's new mortgage lending can go to borrowers above a debt-to-income ratio of 6x for owner-occupiers and 7x for investors. Unlike LVR restrictions, which cap your deposit size, DTI caps how large your total debt can be relative to your gross income — a separate hurdle that sits alongside serviceability testing, not instead of it.
How DTI Is Calculated
DTI = total debt ÷ gross annual income. Total debt includes the new mortgage you're applying for, any existing mortgage balances on other properties, and typically the full limit (not the balance) of credit cards, overdrafts, car loans, and personal loans. A couple earning a combined $140,000 borrowing $650,000 with no other debt sits at a DTI of 4.6x — comfortably under the 6x owner-occupier cap.
Why DTI Exists Alongside LVR and Serviceability Tests
LVR rules cap your deposit, serviceability testing checks you can afford repayments at a stress-tested rate, and DTI caps how many multiples of income your total debt can reach. The Reserve Bank added DTI because a borrower can sometimes pass a serviceability test on a low interest rate but still carry a level of debt that becomes risky if rates rise or income falls — DTI is a structural backstop on top of the rate-based test.
New Builds Are Exempt
Loans for genuine new-build properties are exempt from the DTI restriction entirely, regardless of the resulting ratio — part of the same policy design that carries the new-build LVR exemption. This is one of the reasons new-build purchases can be materially easier to finance for borrowers who are debt-heavy relative to income.
Each Bank Has Its Own Monthly Exemption Quota
The DTI restriction is a "speed limit," not an absolute ban — each NZ bank can still write a limited share of its new lending above the cap each month. Because banks use up that quota at different rates, a scenario declined for being above DTI at one lender can sometimes still be approved at another with headroom left. Knowing which lender has quota available in a given month is exactly the kind of timing knowledge an independent broker tracks.
How to Improve Your DTI Before Applying
- Pay down or close car loans, personal loans, and hire purchase agreements before applying.
- Reduce credit card limits — DTI counts the limit, not the balance.
- Consolidate other-property mortgage balances where refinancing makes sense.
- Consider a genuine new-build property, which sits outside the DTI restriction entirely.
- Increase declared household income sources the bank will count — see our borrowing power calculator.
Read the full breakdown in our DTI rules NZ guide, with worked examples and exemption detail.