The True Cost of Owning a Home — A 10-Year Model
Owning a home costs more than the mortgage payment. Over 10 years, a $750,000 property with a $600,000 mortgage will cost an estimated $640,000 in total ownership outgoings — roughly $534,000 in mortgage payments plus over $100,000 in rates, insurance, maintenance, and rate cycle adjustments. Understanding the full picture from the start helps you plan properly.
This guide vs the Hidden Costs guide
The Hidden Costs of Buying a Home guide covers the upfront and first-year surprises — stamp duty, legal fees, inspections, moving costs, and the immediate costs new owners often underestimate.
This guide covers the full decade — when maintenance accumulates, when rate cycles add to repayments, when major repair cycles hit, and when insurance inflation becomes a budget line item you can no longer ignore. The 10-year view is where the true cost of homeownership becomes apparent.
10-year ownership cost model — $750,000 property
The model below tracks a $750,000 property with a $600,000 principal and interest loan starting at 5.85%. Non-mortgage costs increase over time reflecting rate cycle exposure, maintenance accumulation, and insurance inflation.
Total over 10 years: approximately $640,000 — of which ~$534,000 is mortgage repayments and ~$106,000 is non-mortgage ownership costs (rates, insurance, maintenance, rate cycle adjustments). This is illustrative — actual costs depend on rate changes, property condition, and capital growth. It is intended to show the compounding nature of ongoing ownership costs over time.
Assumptions: $600,000 loan, 5.85% starting rate (variable), $750,000 property, principal and interest. Rate cycle adjustments are indicative based on historical Australian rate cycles, not a prediction.
Mortgage cost over time — where your payments go
In the early years of a principal and interest mortgage, the majority of each repayment covers interest. On a $600,000 loan at 5.85% in year one, approximately $34,000 of the $53,400 annual repayment goes to interest — only $19,400 reduces the loan balance.
By year 10, the split begins to shift. You have repaid approximately $90,000–$100,000 in principal over the decade, but you still owe approximately $500,000. The loan reduces slowly in the first decade of a 30-year mortgage because of how interest is calculated — front-loaded in the early years.
Maintenance accumulation
New properties have low maintenance costs — typically 0.5% or less of property value in the first few years. As a property ages, costs increase. Major repair cycles tend to cluster around 10–15 years after construction: roof repointing or replacement, hot water system, HVAC, gutters, painting, flooring.
A useful rule of thumb: budget 0.5% of property value per year in years 1–5, increasing to 1% in years 5–10, and 1–1.5% thereafter for older properties. On a $750,000 property, 1% is $7,500/year. In a bad year (major roof work, HVAC replacement), costs can spike to $15,000–$30,000.
Rate cycles over a 30-year mortgage
Australian interest rates over the last two decades: 7.25% in 2008 → 2.5% in 2013 → 1.5% in 2019 → 0.1% in 2021 → 4.35% in 2023. Over a 30-year mortgage, you will experience multiple cycles of similar magnitude. The 2022–2023 cycle added over $1,200/month to repayments on a $600,000 loan from trough to peak.
Stress-testing at +2% from today's rate is a minimum. That scenario — a 2% increase from any starting rate — has occurred within the last 2–3 years for Australian mortgage holders. See the Interest Rate Risk guide for the full sensitivity table.
Insurance cost inflation
Insurance premiums have risen 10–20% annually in some Australian markets due to climate risk repricing — particularly in flood-prone, cyclone-exposed, or bushfire-adjacent areas. This is not uniform across Australia, but it is a growing factor in ownership cost.
Budget for premium increases of 5–10% per year as a conservative assumption. On a $2,000 current premium, a 7% annual increase reaches $3,900 by year 10. For properties in climate-exposed areas, the increase can be more dramatic.
What this means for your buying decision
When evaluating affordability, add all non-mortgage ownership costs to your mortgage repayment and assess the total as a percentage of your take-home pay:
- ✓Under 35% of take-home pay: manageable for most households with some budget flexibility
- →35–40% of take-home pay: tight but viable with careful budgeting and limited discretionary spending
- ⚠Over 40% of take-home pay: financially strained — limited capacity to absorb rate increases, maintenance spikes, or income disruption
If your total ownership cost percentage is above 40%, consider whether the purchase price is appropriate for your household income — or whether additional saving to reduce the loan would bring the ratio to a more sustainable level.