Interest Only vs P&I Investment Loans: Which Is Better?

Interest Only vs Principal and Interest for Investors

The interest only vs P&I investment decision changes your cash flow, your tax position and how fast you build equity. Interest only keeps repayments low for a set term. Principal and interest costs more monthly but actually reduces the debt.

Neither is universally right. What matters is your strategy, your buffer, and whether you can absorb the repayment jump when an interest only term ends. This guide covers both sides honestly.

A Loan For You models both repayment types against your real numbers before you commit - at no cost to you. Book a free investment loan review.

Key Highlights

Interest only means you repay just the interest for a set term, usually one to five years, so the balance does not reduce.
Principal and interest repayments reduce the loan balance from the first month.
Interest only usually carries a rate premium over principal and interest.
When an interest only term ends, repayments jump because the balance must be repaid over a shorter remaining period.
Lenders assess interest only applications on the higher post-expiry repayment, which can reduce your borrowing capacity.
Interest on investment borrowing is generally deductible; repaying principal is not.
An offset account alongside interest only can give flexibility without locking money into the loan.

Quick Summary

In the interest only vs P&I investment choice, interest only maximises short-term cash flow and deductible interest, while principal and interest builds equity and usually costs less overall. Plan for the repayment jump either way.

Interest only is a cash flow tool, not a free ride. The investors who get caught out are the ones who never planned for what happens when the term ends.
Philip Jenkins, A Loan For You

Interest Only vs P&I Investment at a Glance

Feature	Interest only	Principal and interest
Monthly repayment	Lower	Higher
Loan balance	Stays the same	Reduces each month
Interest rate	Usually a premium	Usually lower
Equity building	Only from growth	From growth and repayments
Total cost	Higher over the full loan	Lower over the full loan
Term available	Usually 1 to 5 years	Full loan term

How Interest Only Works

During an interest only term you pay just the interest charged each month. The balance you owe at the end of the term is exactly what you started with.

Repayments are noticeably lower during the term.
The full loan balance remains outstanding throughout.
Terms are usually one to five years, sometimes extendable.

Investors use it to preserve cash flow, particularly in the early years when rent may not cover the full holding cost.

How Principal and Interest Works

Each repayment covers the interest charged plus a portion of the balance, so the debt shrinks steadily from the beginning.

You build equity from your own repayments, not just from growth.
The rate is usually lower than the equivalent interest only rate.
Total interest paid over the loan is significantly lower.

It costs more each month, but every dollar of principal repaid permanently reduces the interest you pay from then on.

Interest Only vs P&I Investment: The Tax Angle

Interest on borrowing used to produce rental income is generally deductible. Repaying principal is not a deductible expense, because it reduces your own debt.

That is why some investors prefer interest only on investment debt while directing spare cash at non-deductible debt, such as their own home loan.

This is a general principle, not advice. How it applies depends on your structure and circumstances, so confirm it with your accountant. Our guide to positive vs negative gearing explains the wider tax picture.

The Repayment Cliff at Expiry

This is the single biggest risk with interest only, and it is entirely predictable. When the term ends, the loan converts to principal and interest.

Because the balance has not reduced, it must now be repaid over a shorter remaining term. A five year interest only period on a thirty year loan leaves twenty five years to repay the full amount.

Repayments can rise sharply, sometimes by a third or more.
The increase arrives on a set date, so it can be planned for.
Extending the interest only term requires a new assessment and is not guaranteed.

Diarise your expiry date the day you settle. Reviewing three to six months beforehand gives you options rather than surprises.

How Interest Only vs P&I Investment Affects Borrowing Capacity

Lenders do not assess interest only loans on the low repayment. They assess them on what the repayment becomes after the term ends.

The assessment uses principal and interest over the shorter remaining term.
A buffer above the actual rate is then applied on top.
This can reduce how much you are able to borrow overall.

So choosing interest only for cash flow can slightly limit the size of the purchase you qualify for.

When Interest Only Makes Sense

In the interest only vs P&I investment comparison, there are clear situations where interest only genuinely fits the strategy.

You still have non-deductible debt, such as your own home loan, to attack first.
The property is negatively geared and you need the cash flow buffer.
You are renovating and expect to sell or refinance within the term.
Your income is variable and lower fixed commitments give you room.

When Principal and Interest Makes Sense

For many investors, especially those building a long-term hold portfolio, principal and interest is the quieter and cheaper option.

You want equity built by repayments as well as market growth.
You have no non-deductible debt left to prioritise.
You prefer the lower rate and lower lifetime cost.
You would rather avoid a repayment jump entirely.

A Simple Worked Comparison

Consider a $500,000 investment loan on a thirty year term, with five years taken as interest only.

During those five years, repayments cover interest only and the balance stays at $500,000.
At expiry, that same $500,000 must be repaid over the remaining twenty five years.
The repayment steps up noticeably, because the principal is now compressed into a shorter window.

Had the loan been principal and interest from the start, the balance would already have reduced and no step-up would occur.

Neither path is wrong. The point is that the cash flow you enjoy early is repaid later, so the choice should match a plan rather than a preference for lower repayments now.

Use an Offset Either Way

An offset account sits alongside the loan and reduces the balance interest is charged on, without permanently repaying the debt.

It gives you the interest saving of a repayment, with access to the funds.
It preserves the deductible loan balance, unlike a direct repayment.
It works with either repayment type, and is worth asking for.

If you are funding the deposit from your own home, our guide to using equity to invest explains how to keep the structures separate.

Frequently Asked Questions

Is interest only or P&I better for an investment property?

The interest only vs P&I investment answer depends on your strategy. Interest only maximises cash flow and deductible interest in the short term. Principal and interest builds equity and costs less over the life of the loan.

What happens when my interest only term ends?

The loan converts to principal and interest. Because the balance has not reduced, it is repaid over a shorter remaining term, so repayments can rise sharply. Review your options three to six months before expiry.

Are interest only rates higher?

Usually, yes. Lenders generally price interest only loans above the equivalent principal and interest rate, particularly for investment lending. That premium should be factored into your cash flow comparison from the start.

Does interest only reduce my borrowing capacity?

It can. Lenders assess the loan on the higher repayment that applies after the interest only term ends, then add a buffer on top. That stricter assessment can reduce the amount you qualify for.

Is interest on an investment loan tax deductible?

Interest on borrowing used to produce rental income is generally deductible, while principal repayments are not. How this applies depends on your structure and circumstances, so confirm the detail with your accountant.

Can I extend an interest only term?

Sometimes. Extensions require a new assessment and are not guaranteed, particularly if your circumstances have changed. Plan on the term ending as scheduled, and treat any extension as a bonus rather than the base case.

Should I use an offset account with interest only?

It is often a strong combination. An offset reduces the balance interest is calculated on while keeping your funds accessible, and it preserves the loan balance rather than permanently repaying it.

Which option builds equity faster?

Principal and interest, because every repayment reduces the balance. With interest only, equity grows only if the property value rises, so you are relying entirely on the market rather than your own repayments.

Talk to a Brisbane Investment Loan Specialist

Getting the interest only vs P&I investment structure right affects your cash flow for years. A Loan For You models both against your real numbers, including the repayment at expiry.

As your dedicated Property & Investment Loan Broker in Brisbane, we model interest-only and P&I structures against your actual numbers, so you know exactly what happens at expiry before you commit.

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Reviewed and Verified

This guide was reviewed by Philip Jenkins, principal broker at A Loan For You (Credit Representative 365865). With almost 20 years structuring investment lending for Brisbane clients, Philip keeps every point aligned with current lender policy.

General information only, not tax or financial advice, and correct as at July 2026. Lender and tax rules change - confirm your position with your broker and accountant, and read independent guidance at Moneysmart before you act.