Buying your second, third and fourth investment property: how servicing changes each time

Published 10 July 2026 · Updated 10 July 2026 · 6 min read · By Shane Heness, mortgage broker

Most investors are surprised by property two. The first one went smoothly, the rent covers the repayment, and then the bank says no to the next one. The maths behind that is worth understanding before you plan a portfolio around it.

The three things that shrink capacity each time

1. The assessment rate

Lenders do not assess your loan at the rate you will pay. They add a buffer, generally around three percentage points, to test whether you could still afford the loan if rates rose. A loan at 6% gets assessed at roughly 9%. Applied across a portfolio, that buffer compounds: four loans assessed three points high is a very different picture from four loans at their actual rates.

2. Rental shading

Lenders do not count all your rent either. Most apply a haircut of around 20% to allow for vacancy, management fees, rates and maintenance. Only about 80% of the rent makes it into the calculation.

3. Existing debt counted in full

Every other loan you hold is counted at its assessed repayment, including loans with other lenders. Credit card limits are counted as if fully drawn, whether or not you use them, usually at around 3.8% of the limit per month.

Illustrative only. Assessment rates, shading percentages and repayment calculations vary by lender and change over time.

That difference, roughly $1,900 a month in this example, is what disappears from your capacity for the next purchase. It is not a mistake in the calculator. It is the calculator doing its job.

What changes at each property

Debt-to-income: the ceiling most investors hit

Debt-to-income, or DTI, is total debt across every lender divided by gross household income. A household earning $200,000 with $1.2 million of debt has a DTI of six. Most lenders treat six as the point where a file gets extra scrutiny, and several will not go beyond it at all. A handful will, at a price.

On typical Western Sydney incomes and typical Western Sydney prices, DTI is what stops the fourth purchase, not the deposit. Investors who are planning a portfolio and have not looked at their DTI are usually planning against the wrong constraint.

What moves DTI

• Paying down debt, which is slow but certain.
• Increasing income, including rent that is now counted after twelve months of history.
• Closing unused credit card limits. A $30,000 unused limit counts as $30,000 of debt.
• Selling a low-performing asset to recycle the debt into a better one.

Sequencing: the part brokers actually add

Lenders differ, and the differences are large enough to change what you can buy. Some shade rent at 20%, some at 10%, some count negative gearing benefits and some do not. Some assess your existing loans with other lenders at their actual repayment, others at their own assessment rate.

The practical implication is that the order matters. Use the most generous lender first and you have spent your best option on a purchase that any lender would have approved. Use them last, when your file is hardest, and they are there when you need them.

That is the single biggest thing we do for portfolio clients. We map out the next three purchases and decide, now, which lender each one should go to, so the easy deals go to the tight lenders and the hard deals go to the generous ones.

Structuring mistakes that cost you the next purchase

Cross-collateralisation

Where one lender holds two or more of your properties as security for the same loans. It feels efficient and it is not. It ties your properties together, makes selling one complicated, and hands a single lender control over your whole position. Keep each property standing on its own security wherever possible.

Redraw instead of offset

Paying extra into an investment loan and redrawing it later can change the tax deductibility of that portion. An offset account achieves the same cash flow result without touching the loan balance. This is a conversation for your accountant, but the loan has to be set up to allow it.

Taking the whole equity release at once

Releasing equity in one large lump and parking it can hurt servicing, because the full loan is counted whether or not the funds are deployed. Releasing in line with what you are actually about to buy usually tests better.

A realistic plan for the next purchase

1. Get a current read on your actual capacity across several lenders, not one.
2. Calculate your DTI now, before you go looking.
3. Clear or reduce credit card limits you are not using.
4. Check whether the equity you think you have is supported by a current valuation.
5. Decide which lender this purchase goes to and which lender the one after goes to.

The equity question: what you have versus what you can use

Most investors overestimate their usable equity, because they count the gap between what they owe and what the property is worth. Lenders do not calculate it that way.

Usable equity is generally 80% of the current valuation, less the existing loan balance. The 20% buffer is not available to you, because releasing it would take the loan above 80% and trigger lender's mortgage insurance on the release.

Illustrative only. Valuations are lender ordered and frequently come in below owner expectations.

The portfolio above shows $840,000 of raw equity and $396,000 of usable equity, and almost all of the usable figure sits in one property. That is normal. It is also why an accurate valuation matters: a $50,000 difference in the home's valuation moves the usable figure by $40,000, which is often the difference between a deposit and no deposit.

Having usable equity is not the same as being able to borrow against it. Equity gives you the deposit. Servicing decides whether you get the loan. Investors regularly arrive with plenty of equity and no capacity, and equity alone will not fix that.

Most investors we work with own between one and five properties, and the conversation is almost always about sequencing rather than rate. Our investment loans page covers how we structure these, and if you want a read on where your capacity actually sits, book a free call.

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Written by Shane Heness

Owner and mortgage broker at LoanBuddy, Parramatta NSW. Eight years as a mortgage broker and a property investor since 2015. Credit Representative #528658 under Australian Credit Licence #389328.