What does DTI actually stand for?

DTI stands for debt-to-income ratio. It's a simple calculation: your total debt divided by your gross (before-tax) annual income.

So if your household earns $120,000 a year and you want to borrow $600,000, your DTI would be 5.

In July 2024, the Reserve Bank of New Zealand (RBNZ) introduced formal DTI limits. Banks are now restricted from lending more than:

• 6 times the gross income of owner-occupiers
• 7 times the gross income of property investors

That cap matters. No matter how good your credit history is or how comfortably you could afford the repayments, there's now a ceiling on what most lenders can offer.

Tip: Multiply your combined household gross income by 6. That's roughly your maximum borrowing limit under current DTI rules — a useful number to have before you start looking at properties.

Why did the RBNZ bring in DTI limits?

The RBNZ introduced DTI limits to reduce risk across the financial system. Heavily indebted borrowers are more vulnerable when interest rates rise or jobs are lost — and that vulnerability can ripple out into the broader economy.

Banks can still lend above the DTI cap in a small number of cases — the rules allow a portion of their lending book to sit outside the limits. But you shouldn't plan around being the exception.

Tip: DTI limits work alongside LVR (loan-to-value ratio) restrictions — another RBNZ tool. You need to satisfy both to get a standard mortgage.

What debt counts in a DTI calculation?

This is where things get detailed. DTI includes all existing debt, not just the new mortgage you're applying for:

• The mortgage you're applying for
• Any other mortgages (investment properties, for example)
• Car loans
• Personal loans
• Student loans
• Credit card limits — even if you haven't used them

That last point trips people up. If you have a $15,000 credit card limit sitting unused, many lenders still count it as potential debt. Reducing or closing unused cards before you apply can genuinely shift your DTI.

Tip: Before you apply, do a full debt audit. Cancel unused credit cards and pay down what you can — it makes a bigger difference than most people expect.

How do DTI rules affect first home buyers?

First home buyers often have lower incomes than more established buyers, which means the DTI cap can feel tight — particularly in Auckland and other higher-priced markets.

Buying as a couple or with a co-borrower can significantly increase your ceiling. A single buyer on $75,000 a year has a maximum borrowing limit of around $450,000. A couple earning $140,000 combined can potentially borrow up to $840,000.

The good news: tools like KiwiSaver withdrawals and the First Home Grant (if you qualify) boost your deposit rather than your debt — so they don't affect your DTI at all.

Tip: Use every available deposit tool — KiwiSaver, the First Home Grant, family gifting — to reduce your loan size. A smaller loan means a lower DTI.

What can you do if your DTI is too high?

If you're bumping against the DTI limit for the property you want, there are a few practical paths:

1. Pay down existing debt — even clearing a small personal loan can move the needle
2. Close or reduce unused credit card limits
3. Increase your income — a pay rise, a side income, or adding a co-borrower all help
4. Look at a lower-priced property
5. Wait and save — as you pay down debt over time, your DTI naturally improves

At Mortgage Mates, we work through DTI calculations with clients before they apply for anything. Knowing your position upfront means no nasty surprises — and we can help you spot which lenders might have a bit more flexibility in your situation.

Does working with a mortgage broker help with DTI?

Yes — and this is one of the most practical reasons to use a broker. Different lenders calculate DTI slightly differently, and some treat certain debts more generously than others. A broker who knows the market can match you with a lender whose approach suits your situation.

Mortgage Mates works with a wide range of lenders, and we can run your numbers across different bank policies before you submit a single application. That protects your time — and your credit score.

Tip: Talk to a mortgage broker before approaching a bank. Understanding where you sit on DTI first means you apply with confidence — not guesswork.

Ready to work out your numbers?

DTI rules don't have to be a roadblock. They just need to be part of your planning. If you'd like to know where you stand and what your options look like, book a free chat with the Mortgage Mates team. We'll walk you through it in plain English, no pressure.

Key Takeaways:

• DTI stands for debt-to-income ratio — total debt divided by gross annual income
• The RBNZ introduced DTI limits in July 2024: up to 6× income for owner-occupiers, 7× for investors
• All debt counts — including credit card limits, car loans, and existing mortgages
• Strategies to improve your DTI include paying down debt, closing unused credit cards, and boosting your deposit
• A mortgage broker can match you with lenders whose DTI approach works best for your situation

FAQ:

Q: What is a DTI ratio in NZ mortgages?
A: DTI stands for debt-to-income ratio. It's your total debt divided by your gross annual income. The RBNZ limits banks to lending up to 6× income for owner-occupiers and 7× for investors.

Q: When did New Zealand introduce DTI limits?
A: The Reserve Bank of New Zealand introduced formal DTI limits in July 2024 as a macro-prudential tool to reduce financial system risk.

Q: Does a credit card limit count in a DTI calculation even if I don't use it?
A: Yes, in most cases. Many lenders count your total credit card limit — not your balance — as potential debt. Closing or reducing unused cards before applying can lower your DTI.

Q: Can I borrow more than 6 times my income?
A: Banks can lend a small portion of their book above DTI limits, but you shouldn't rely on it. A mortgage broker can help identify lenders with a bit more flexibility for your circumstances.

Q: Does KiwiSaver help with DTI?
A: KiwiSaver funds go towards your deposit, which reduces the size of your loan. A smaller loan means a lower DTI — so yes, maximising your deposit is one of the best ways to stay within DTI limits.

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