Investment Property Cash Flow Explained

Cash flow is every dollar the property brings in, minus every dollar it drags out, over a month or a year. Not the purchase price, not projected growth, not the brochure yield — just money in, money out.

It's the least glamorous number in property and the one most likely to decide whether you keep the place. So let's do the maths the listing never will.

The 'in' column is short: rent, and occasionally an insurance payout. The 'out' column never ends — loan interest, council rates, water, insurance, property management fees, maintenance, strata levies if it's an apartment, plus a few vacant weeks a year when no rent arrives.

A realistic year: rent of $550 a week brings in $28,600. Interest on a large loan might run around $31,000, and other running costs another $9,000 or so. That's roughly $40,000 out against $28,600 in — a shortfall of about $11,000 to $12,000 a year, or close to $1,000 a month, before tax.

That's your pre-tax cash flow: rent minus costs, no tax effects. For most Australians buying with a big loan it's negative. That's not automatically a mistake — but it is a monthly bill.

A rental loss is deductible — you subtract it from your salary before tax is worked out — which is negative gearing doing its job. Depreciation (claiming the slow wearing-out of the building as a yearly expense) adds a deduction that never touched your wallet.

Say the pre-tax hole is $12,000 and a depreciation schedule adds $8,000 of paper deductions: a $20,000 tax loss. If you earn between $45,001 and $135,000, your marginal rate — the tax rate on your top dollar — is 30%, plus the 2% Medicare levy, so the loss returns about $6,400 at tax time.

After tax, the $12,000 hole shrinks to roughly $5,600 a year — about $470 a month, or $108 a week. That's your after-tax cash flow: the true cost of holding the property once the refund lands. Still negative, just smaller.

The costs are monthly, but the refund is yearly. Your lender wants interest every month, the council wants rates every quarter, and the ATO's contribution shows up once, after you lodge your return.

So you live on pre-tax cash flow for eleven months and get rescued in month twelve. If your budget can't carry the monthly hole, the annual refund is cold comfort.

The workaround is a PAYG withholding variation — an ATO form that lets your employer take less tax from each pay to reflect your expected rental loss, effectively drip-feeding the refund into your pay. Ask a tax professional about it if the monthly gap is tight.

The number that matters is the worst realistic month: interest after a couple of rate rises, a four-week vacancy, and a dead hot water system. Can you cover that month from your income and buffer without touching the groceries?

If yes, negative cash flow can be a deliberate strategy — a known monthly cost in exchange for a shot at capital growth. If no, you own a stress subscription with a property attached.

Rate moves deserve respect: on a $500,000-plus loan, each 1% rise adds thousands a year to the out column, and the tax refund only hands back about a third of it. Stress-test before you buy.