A quick heads-up: The information in this article is designed as a general educational guide only and does not constitute personalised financial, tax, or legal advice. Because everyone's situation is unique (and bank policies change frequently), we recommend speaking with a licensed Financial Adviser to see how this applies to your specific circumstances. For full transparency on our terms of service, how we are remunerated by lenders, and any specific situations where a fee may apply, please read How We Get Paid.
Almost without fail, the very first question people ask us is: How much can I actually borrow?
It sounds like a simple maths question, but the real answer is rarely a single, neat figure. If a mortgage adviser seems hesitant to spit out an exact dollar amount on the spot, they are not dodging the question. It is simply because your borrowing power is a moving target shaped by your deposit, your daily spending habits, and strict banking rules.
The baseline guide: four to six times your income
To get a sensible starting estimate, look at your gross (before-tax) household income.
The Reserve Bank of New Zealand (RBNZ) enforces formal Debt-to-Income (DTI) restrictions. For owner-occupiers, banks are generally restricted from lending more than six times your gross household income (or seven times for property investors).
However, just because six times your income is the regulatory ceiling does not mean a lender will automatically hand you that amount. Once the bank applies its internal servicing calculations, most approved loans land somewhere between four to six times your income.
Running the maths
If a couple earns a combined $100,000 before tax, their borrowing capacity will typically sit between $400,000 and $600,000.
To estimate your target purchase price, add your cash deposit and KiwiSaver savings to that lending figure:
- Bank lending: $400,000 to $600,000
- Plus your deposit: $150,000
- Estimated purchase price: $550,000 to $750,000
That is clearly a broad bracket. Where your application lands within that range depends on how the bank tests your day-to-day outgoings.
Why banks often lend less than online calculators suggest
When you run your numbers through basic online mortgage calculators using current fixed rates, the weekly repayments can look very manageable. Yet when you apply, the bank might offer significantly less.
Here are the four main reasons that happens:
1. The bank test interest rate
Banks do not assess your mortgage application using today's advertised special rates. To make sure you can still comfortably afford repayments if the market changes, they test your income against an artificial stress-test rate—often sitting 1.5% to 2.5% higher than actual carded interest rates. If your budget cannot handle that higher theoretical rate, the bank trims your loan amount until it does.
Read more on how banks stress test your income
2. Fixed salary deductions and student loans
Every non-negotiable deduction from your pay reduces the cash available to service a mortgage:
- Student loans: In New Zealand, the mandatory 12% deduction on income earned above the repayment threshold directly reduces your usable take-home pay in the bank's servicing calculator.
- Child support and court-ordered payments: These are treated as fixed, non-negotiable outgoings.
- Dependants: Banks apply standard benchmark living costs. The more children or financial dependants in your household, the higher the bank's baseline living cost estimate, which reduces your spare borrowing margin.
Read more on how childcare costs can affect your borrowing power.
3. Credit limits, overdrafts, and short-term debt
Banks assess credit cards on their total approved credit limit, not what you actually owe.
A $10,000 credit card limit—even if the balance sits at zero every single month—can reduce your mortgage borrowing power by roughly $45,000 to $50,000. Buy Now Pay Later facilities like Afterpay or Zip, everyday account overdrafts, and car finance also place an immediate squeeze on your borrowing capacity.
Read more about how credit card limits can affect your borrowing power.
4. Overtime, bonuses, and commission
Read more on how banks think about overtime, bonuses and commission.
Practical ways to lift your borrowing power
If your initial figures do not quite reach the house price you are aiming for, you have several practical options to push your capacity closer to that six-times ceiling:
- Cancel or reduce credit card limits: Trimming a $10,000 limit down to $2,000, or closing the card entirely, is the fastest single way to restore borrowing capacity. (Check with an adviser first though!)
- Clear short-term personal and car loans: Eliminating high-interest monthly payments frees up direct cash flow in the bank's servicing calculator. A quick note on strategy: Always check with an adviser before using cash savings to clear debts, as you don't want to accidentally shrink your cash deposit below your minimum deposit requirements.
- Include boarder or flatmate income: If you are buying a property with spare bedrooms, many mainstream lenders allow you to count declared boarder income (typically $150 to $200 per week, per room) toward your application.
- Leverage upcoming pay rises: If you have a confirmed salary increase on the horizon or you are about to move off a probation period, let us know! We don't necessarily need to wait for it to take effect before submitting. With a signed employment agreement or variation letter in hand, we can often get your loan approved subject to providing your first new payslip, getting you house-hunting sooner.
Pinning down your actual borrowing figure
Generic online calculators give a rough snapshot, but they treat everyone with the same broad brush. Because every bank interprets living expenses, variable income, and flatmate declarations slightly differently, a bespoke assessment is the only way to establish your genuine borrowing power.
To get started right now, try our Borrowing Power Calculator. It calculates similarly to the way banks do to give you an estimate of what you might be able to achieve.
Once you have run your numbers, a quick 15-minute chat gives us enough detail to narrow that range into a clear, realistic borrowing estimate figure. We can also identify which small adjustments—like closing a dormant credit facility—will deliver the biggest lift to your approval amount before your application ever goes in front of a bank credit team.
Want to establish your true borrowing range? Test your numbers on our Borrowing Power Calculator or book a free strategy chat with the Home Loan Factory team today.
