On a combined household income of $100,000 in New Zealand, the RBNZ’s DTI 6x rule sets a maximum joint mortgage of $600,000 — assuming neither borrower has significant existing debt. Here is what that means for your purchasing power and repayments.
On a combined income of $100,000 with no existing debt, the DTI 6x maximum joint mortgage is $600,000. With a 20% deposit of $150,000, you can target properties up to $750,000. Monthly repayments at 5.50% over 30 years: approximately $3,407/month.
Joint Borrowing Capacity at $100,000
Under DTI 6x, combined gross income is multiplied by 6 to get the maximum loan:
| Amount | |
|---|---|
| Combined gross income | $100,000 |
| DTI maximum mortgage | $600,000 |
| Maximum purchase price (20% deposit) | ~$750,000 |
| 20% deposit required | $150,000 |
| Monthly repayment (5.50%, 30yr) | $3,407 |
Example income split: Two incomes of $50,000 each.
Important: Both borrowers’ existing debts are combined in the DTI calculation. If one partner has a $20,000 car loan and the other has a $30,000 student loan, the combined DTI capacity falls from $600,000 to $550,000.
Repayments on $600,000 at Different Rates
| Rate | Monthly | Fortnightly | Weekly |
|---|---|---|---|
| 5.20% | $3,295 | $1,521 | $760 |
| 5.50% | $3,407 | $1,572 | $786 |
| 5.80% | $3,521 | $1,625 | $812 |
| 6.20% | $3,675 | $1,696 | $848 |
| 6.50% | $3,792 | $1,750 | $875 |
Joint Mortgage vs Solo Mortgage
The power of a joint income for mortgage borrowing is significant:
| Income | DTI max mortgage | Max property (20% dep) |
|---|---|---|
| Solo $100,000 | $50,000* | ~$8,333 |
| Combined $100,000 | $600,000 | ~$750,000 |
*Assuming equal split. In practice, either partner borrowing solo on half the income.
This illustrates why joint applications unlock significantly more purchasing power — and why two moderate incomes can often access more than one high income.
Joint Liability: What You Need to Know
A joint mortgage means joint and several liability — each borrower is fully responsible for 100% of the debt, not just their share. This applies regardless of any private arrangement between the borrowers about how costs are split.
If one borrower stops making repayments, the bank can pursue the other for the full outstanding balance. Before entering a joint mortgage with anyone other than a long-term partner, consider getting a formal legal agreement in place.
See the joint mortgage guide for full details.
Frequently Asked Questions
How much can we borrow on a combined income of $100,000 in NZ?
With no existing debt, DTI 6x gives a maximum of $600,000. With a 20% deposit of $150,000, you can target properties up to $750,000. Any existing debts from either borrower reduce this.
Do both our incomes count for a joint mortgage in NZ?
Yes — both borrowers’ gross incomes are combined in the DTI calculation. This is one of the main advantages of joint applications. Both borrowers’ debts, credit card limits, and living expenses are also assessed together.
What is the DTI limit for couples buying a home in NZ?
The same 6x rule applies to joint applicants as to individual borrowers — total debt (new mortgage plus all existing debt) cannot exceed 6x combined gross annual income for owner-occupiers.
What happens to the mortgage if we separate?
Separation requires resolving the relationship property settlement before the mortgage can be restructured. The remaining partner needs to qualify solo under current DTI and serviceability rules to keep the property. See the separation mortgage guide.
What deposit do we need for a joint mortgage of $600,000 in NZ?
The standard 20% deposit on a $750,000 property is $150,000. This can come from savings, KiwiSaver first home withdrawals, gifted funds (with a statutory declaration), or a combination.