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Understanding cash flow is a critical element of the investment property game writes Michael Sloan. It can make be the difference between a solid long-term investment and a costly mistake. So do your research – and get good advice – before you buy.

Give me the main points

  • Many investment properties generate negative cash flow.
  • That is, the cost of the property (mortgage repayments, rates, etc.) exceeds rental income and the tax breaks the investor receives.
  • Miscalculating cash flow is common – it’s tempting to fall for best-case scenarios.
  • Factor in potential interest rate rises – and also potential vacant tenancies.
  • Talk to your accountant – or banker or financial advisor – before you take the plunge.

What is negative cash flow?

Often investment properties generate negative cash flow. That is, you must put money in each year to cover the difference between the total cost of the property (interest repayments, rates, insurance, maintenance, etc.) and the total income (rent and tax breaks). Investors are happy to do this because they expect a long-term profit. And over time the rental increases that accompany inflation should mean this ‘top-up’ is no longer necessary.

Unfortunately some investors don’t know the cash flow of their property before they buy. They don’t realise something’s wrong until their cash flow dries up and they get the bad news from their accountant. So seek advice from your accountant before you buy, not after. Always do the numbers first.

Miscalculating cash flow

It’s easy to miscalculate cash flow. Your estimated rental income might be over-optimistic, and you might also assume full occupancy (ie. 52 weeks a year). Conversely, you might underestimate maintenance costs or insurance.

Investors who get the cash flow of their property wrong can quickly run into problems. They either have to raise additional cash to prop up their property each month (potentially putting them under great financial stress), or sell. Selling property under pressure is never ideal and these investors can lose big. Sadly, this is a common mistake.

Work out your cash flow

To understand the cash flow on a potential investment property, get your accountant to do the numbers for you (if they can’t, get a new accountant). The number one rule is: ‘Don’t buy a property without knowing what the cash flow is’.

Ensure your accountant has all the costs of holding the property, including rates, body corporate insurance property management fees. They can work out the interest, estimate depreciation and give you an idea of the cash flow. If buying that property will put strain on your finances, then find a property with better cash flow. Also when doing your figures, factor in possible interest rate rises and potential vacancies.

Further, if the company selling you a property provides a cash flow report, don’t take it as gospel. The figures can always be manipulated, so get your accountant to work through them.

Your key to staying safe in a sentence? Understand the cash flow before you buy.

A tip about tax

Most property investors improve their monthly cash flow by applying to the Australian Tax Office (ATO) for a tax variation. This gives them their tax breaks in each wage packet, instead of waiting to the end of the year for a tax refund. Read about PAYG Withholding Variation here.


The information in this article has been written by Michael Sloan from The Successful Investor. While Mr Sloan has been careful to ensure the information is correct and accurate, Mr Sloan’s views are his own and do not necessarily represent those of National Australia Bank Limited ABN 12 004 044 937, AFSL and Australian Credit Licence 230686 (NAB). This information should not be relied upon as financial product advice as none of the information provided takes into account your personal objectives, financial situation or needs. NAB recommends seek the counsel of an independent financial advisor before making any investment decision.

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