What is Debt-to-Income Ratio (DTI) and Why It Matters When Buying a Home

If you’re thinking about buying a home, you’ve probably heard terms like deposit, interest rates, or pre-approval.

But there’s another number that plays a major role – and most people don’t fully understand it.

It’s called Debt-to-Income Ratio, or DTI.

What is DTI?

DTI is a simple way for banks to measure how much you’re borrowing compared to how much you earn.

In plain terms: It shows how many times your income you’re taking on as debt.

A Simple Example

Let’s say:

• You earn $100,000 per year
• You want to borrow $600,000

Your DTI would be: 6

That means you’re borrowing 6 times your annual income.

Why Does This Matter?

DTI is important because banks use it to limit how much you can borrow.

Even if:

• You have a deposit
• You have good credit
• You meet all other requirements

Your DTI can still be the factor that determines your borrowing limit.

What is the Typical DTI in New Zealand?

In New Zealand, most banks currently work around: 6 to 7 times your income

This isn’t a fixed rule – it can vary depending on:

• Your financial situation
• The type of property you’re buying
• The lender you’re working with

But for most people, this is the general range.

Why Banks Use DTI

From a bank’s perspective, it’s about risk.

The higher your DTI:

• The more debt you’re taking on
• The harder it may be to manage repayments if things change

So banks use DTI to ensure: You’re not overextending yourself financially

Are There Exceptions?

Yes – DTI doesn’t always apply in the same way.

Some common situations where flexibility may exist:

• Refinancing an existing loan
• First Home Loan schemes
• Certain new builds

Every situation is different which is why good advice matters.

What Most People Get Wrong

A lot of buyers focus only on:

• “Do I have enough deposit?”
• “Will the bank approve me?”

But the better question is: “How much can I actually borrow based on my income?”

Because your income doesn’t just determine approval – it determines your buying power.

Bringing It All Together

DTI might sound technical, but it’s actually straightforward – it’s a measure of how far your income can stretch when it comes to borrowing.

If you want a simple, real-world explanation, watch our director Mils Muliaina break it down in the video alongside this article.

And if you want to understand your own borrowing power based on your income, have a chat with the team at The Mortgage Hub – our goal is to help you get clear on your options, so you can make the right choice for you and your family.