More from Opes:

• The "Can I Invest?" Test
• How to know if you can really afford an investment property top-up
• What is negative-gearing? and how does it affect my investment property?

How much income do I need to buy an investment property (and is there a minimum)?

On top of the deposit, you’ll probably need a mortgage. And the bank needs to be willing to give you the money for the house.

They won’t automatically give you the money just because you have the deposit.

You also need enough income. They want to make sure that even if a few bad things happen, you can still afford the mortgage.

The income side of a mortgage application is often harder to calculate.

There isn’t one minimum income that guarantees you can invest. But at Opes we generally say it’s worth looking more closely once your household earns around $100,000 a year.

You might use a mortgage calculator, see the repayments and think: “Yup, I can afford that.” But the bank might not agree with you.

This is because the banks run stress-test calculations when deciding whether to give you the mortgage.

These calculations are usually referred to as “servicing”. Can you afford to service the mortgage?

To see the amount you can borrow, use this (loose) ballpark calculation:

(Your income) x 6 = the amount you can borrow

Note: this multiple can change. When interest rates are lower, mortgage advisers will use 7x.

For instance, if you and your partner earn:

• $120k through your jobs, and
• $30k through your rental property

You have $150k in household income. Multiply that by 6 and you get $900k. So, the bank may lend you up to $900k.

But remember, this is for a very rough estimate. It isn’t how the bank makes its final decision.

Instead, they will look at your existing debts, expenses, rental income and whether you can still afford the loan at a higher interest rate. 

Debt-to-income rules also restrict how much high-debt lending banks can offer. 

These are all complicated and technical, so use our calculator to see how much you could potentially borrow based on your income.

How does the bank stress-test my mortgage application?

When you apply for a mortgage the bank doesn’t just test whether you can afford today’s mortgage rate. It uses a higher ‘servicing test rate’ too.

This checks whether you could still afford the loan if interest rates went up.

As of August 2026, the five major banks use test rates between 6.85% and 7.10%.

The tricky part is that these rates aren’t easy to find. 

They pop up in the media sometimes, but they change often, so it’s hard to know what you’re actually being tested against.

Here are the latest servicing test rates:

How much cashflow do investment properties make?

If you borrow most or all of the purchase price, the rent may not cover every cost. You’ll need to pay the difference yourself.

This is sometimes called negative gearing. It’s very common when you borrow all the money to invest in property i.e. you don’t have a cash deposit. 

According to Valocity, a New Zealand property data company, around 90% of investment properties in 2024 were negatively geared.

So, the investor needs to “top-up” the investment property’s mortgage.

In August 2026, this is typically somewhere between $200 – $400 a week.

This is the case whether you invest in a New Build or existing investment property.

For example, here are 3 different properties with the cashflow of each:

This assumes that you’re borrowing all the money to invest. If you have a big cash deposit, the top-ups will be lower.

Cashflow can improve as rents rise or your mortgage rate falls.

There are lots of different factors that impact the cashflow of your property, so you can either use:

• Our property investment cashflow calculator 
• Head to Opes+. This will create a cashflow projection for you 

This will give you a sense of whether you can afford an investment property on an ongoing basis.

Why is the top-up different for each property?

No two properties or mortgages are the same, so top-ups vary based on:

• Purchase price
• Rent earned
• Mortgage size
• Ongoing costs (rates, insurance, maintenance, accounting, vacancy)
• Interest rates

If the costs are higher, or you have a big mortgage, the expenses are higher, so the top-up is larger.

This is why top-ups are more common with the No Cash Needed method (borrowing the full amount). A bigger deposit means a smaller mortgage and usually a smaller top-up.

Keep in mind holding costs can still shift. For instance, if interest rates rise, your top-up rises too, so it’s worth stress-testing the numbers.

The: ‘Can I Invest?’ Test

Let’s say you want to buy an investment property. The rent doesn’t cover all the costs, so you need to top it up by $200 a week.

But you’re not sure whether you can afford that. That’s where you might use the ‘Can I Invest’ Test.

Put that $200 aside every week, as if you have already bought the property.

After 2-3 months, check in:

• Is the money piling up? or
• Have you been taking money out of that account to spend?

If you’ve managed to put the money aside without touching it … you’ve passed the test.

Here’s how to set up the test in 4 minutes:

• Open your bank app (time: 30 seconds)
• Create a new bank account – call it the ‘Can I Invest?’ account (time: 1.5 mins)
• Set up an automatic payment. If your top-up is $200 a week, automatically transfer that money into your ‘Can I Invest?’ account. (time: 2 mins)

If you get paid fortnightly, just do one fortnightly payment ($400 in this case). It doesn’t have to be weekly.

Same deal if you get paid monthly, but it must be automatic.

And it can often be useful if you set it up to automatically transfer the day after you get paid.

That way the money’s already moved before you even think about spending it.

Can I afford an investment property?

To afford an investment property you need more than a deposit. You also need enough income for the bank to lend to you and enough spare cash each week to hold the property.

That’s why the best place to start is with your own numbers.

Do you have enough deposit or usable equity? Will the bank lend you enough? And after paying your normal bills, do you still have enough left over to cover the property’s weekly shortfall?

If you’re not sure about that last one, try the Can I Invest Test. Put the expected top-up aside each week for a few months and see how your budget handles it.

If you can do that comfortably you may be closer to investing than you think.

If you can’t, that’s useful too. It tells you what needs to change before you buy.