How Big Should Your Cash Buffer Be? The Property Investor’s Guide

When an investor is forced to sell, the property is often not the problem. Running out of cash before the property has time to work is. A buffer is what buys you that time, and in a year with a 4.60% cash rate and falling values, sizing it properly matters more than usual.

Why does a cash buffer matter now?

The Reserve Bank’s latest Financial Stability Review found the median borrower could cover more than a year of scheduled mortgage repayments from offset and redraw balances (Reserve Bank of Australia [RBA], 2026). Most borrowers in a cash-flow shortfall have enough savings to cover the gap for at least six months if they cut spending to essentials.

That is the system average. Your buffer is the one that counts, and the RBA has kept further rate increases on the table (Commonwealth Bank of Australia, 2026).

Start with your personal emergency fund

Before you size a property buffer, cover your own household. Moneysmart suggests a good target is enough to cover three months of expenses (Australian Securities and Investments Commission [ASIC], n.d.). Self-employed people, casual workers and single-income households may want six months or more (Thomson & Gearie, 2026).

Keep this separate from your property buffer. If both draw on the same pool, one bad month can empty it twice.

Then size your property buffer

A property buffer should cover four things:

1. Your holding shortfall. Rent minus loan repayments, property management, insurance and rates. Aim for at least six months of any shortfall.

2. A vacancy. National rental vacancy rose to 2.1% in September 2026, the highest since January 2025 (Cotality, 2026). Allow at least four weeks of lost rent per property.

3. A rate rise. Calculate what another 0.50 percentage points would add to your repayments for a year.

4. Repairs and maintenance. A common rule of thumb is about 1% of the property’s value each year (GIO, 2026). Repairs rarely arrive evenly, so hold a year’s worth in cash rather than relying on the monthly average.

A worked example

Take an $800,000 property renting for $650 a week, with a $640,000 principal and interest loan at an assumed 6.85% over 30 years. Assuming insurance of $2,000 a year, council rates of $2,500 and management at 7% of rent, the property runs a pre-tax shortfall of about $23,400 a year before maintenance.

Buffer component	Amount
Six months of holding shortfall	about $11,700
Four weeks of vacancy	$2,600
A 0.50 percentage point rate rise for 12 months	about $2,600
One year of maintenance at 1% of value	$8,000
Property buffer	about $25,000

This is in addition to three months of personal expenses. These are our own calculations, and every figure is an assumption to replace with your own numbers.

Some holding costs are rising faster than rent

In the year to August 2026, insurance rose 5.6% while rents in the CPI rose 3.6% (Australian Bureau of Statistics [ABS], 2026). Advertised rents grew faster, up 5.5% over the year to September (Cotality, 2026), but that growth is slowing. A buffer sized two years ago may be too small today. Review it at least once a year and after every rate change.

Where should you keep your buffer?

An offset account is usually the most efficient place, because cash there reduces the interest charged on your loan while staying available. Moneysmart notes you can use an offset account as your emergency fund (ASIC, n.d.). If you hold several loans, put the buffer against the loan with the highest rate or the non-deductible debt first, and confirm the tax treatment with your accountant.

Avoid using redraw as your only buffer. Lenders can change redraw access, while an offset balance is your own money.

When to build a bigger buffer

• You hold several properties with the same lender or in the same area.
• Your income is variable, commission-based or tied to one employer.
• Your property is older, strata-titled or due for major work.
• You bought with a high LVR and could struggle to refinance if values fall.

Frequently asked questions

How much cash buffer should a property investor have? Enough for three months of personal expenses plus a property buffer covering six months of shortfall, a vacancy, a rate rise and a year of maintenance.

Is an offset account a good place for a cash buffer? Usually. Cash in an offset reduces interest while remaining accessible.

This article is general information only and does not consider your personal circumstances. Speak to a licensed adviser before making financial decisions.