Everyday Money guide
How to Calculate Investment Property Cash Flow
Build a before-tax annual cash-flow forecast from effective rent, operating expenses and loan repayments.
Updated 16 October 2026 • Reviewed by Tools by Layna Editorial Team • General information only
Why this decision is easy to misread
Investment-property cash flow is the money left after rent and other property income are reduced by operating expenses, loan repayments and loan fees. It should be calculated before relying on tax refunds or capital growth.
A before-tax model shows whether the household can carry the property from ordinary cash if tax timing or deductions differ from expectations.
The calculation, step by step
Effective rent
Weekly rent multiplied by occupied weeks, not automatically 52.
In the calculator, this item should be entered separately so a change in effective rent can be tested without hiding it inside another assumption.
Other income
Parking, storage or recoveries only where realistic and permitted.
In the calculator, this item should be entered separately so a change in other income can be tested without hiding it inside another assumption.
Operating expenses
Management, rates, water, strata, insurance, maintenance, land tax and accounting.
In the calculator, this item should be entered separately so a change in operating expenses can be tested without hiding it inside another assumption.
Loan repayment
Include the full cash payment for affordability.
In the calculator, this item should be entered separately so a change in loan repayment can be tested without hiding it inside another assumption.
Interest and principal
Separate them for tax and equity analysis.
In the calculator, this item should be entered separately so a change in interest and principal can be tested without hiding it inside another assumption.
Cash contribution
Negative cash flow is the amount the investor must fund.
In the calculator, this item should be entered separately so a change in cash contribution can be tested without hiding it inside another assumption.
Worked Australian example
Rent of $650 for 50 occupied weeks produces $32,500. If operating expenses are $12,500 and annual loan repayments are $37,000, the before-tax cash flow is negative $17,000.
Part of the $37,000 may reduce principal, so the balance sheet improves even while the bank account requires a contribution. Both facts should be shown.
Decision checklist
| Step | What to confirm |
|---|---|
| 1 | Use realistic occupied weeks. |
| 2 | Annualise every expense. |
| 3 | Model current and stressed interest rates. |
| 4 | Separate principal from interest. |
| 5 | Confirm the household can fund the negative case. |
Use the calculator with this guide
Common mistakes
- Using rent before vacancy.
- Subtracting interest only when cash repayments include principal.
- Calling principal a lost expense in total ROI.
- Relying on a tax refund to make monthly payments.
- Ignoring annual or quarterly bill timing.
Questions to answer before acting
- Use realistic occupied weeks.
- Annualise every expense.
- Model current and stressed interest rates.
- Separate principal from interest.
- Confirm the household can fund the negative case.
Record keeping and review
For this calculation, retain the evidence behind effective rent and other income.
Official sources
Related guides
Frequently asked questions
Is negative cash flow always bad?
Not necessarily, but it must be affordable and justified by the full risk-return case.
Should tax be included?
Analyse before tax first, then obtain personalised after-tax advice.
How do I include repairs?
Use a normal annual allowance and run a separate major-repair stress case.
Does depreciation improve cash flow?
It can affect tax but does not create cash before tax.
What if rent rises?
Model rent growth separately and avoid using it to hide weak first-year affordability.
Bottom line
Cash flow is the property’s demand on the household bank account; calculate it before discussing paper gains.