What happens if your house is underinsured?
Underinsurance: the gap many homeowners don’t see
Home insurance is often treated as a set-and-forget household bill. But insurance specialists and consumer advocates warn that many homeowners may be paying for cover that would not fully protect them if the worst happened. Underinsurance occurs when the amount your policy is set to pay—your “sum insured”—is too low to cover the real cost of rebuilding, repairing or replacing your property.
Fei Huang, an associate professor in the School of Risk and Actuarial Studies at the University of NSW Business School in Sydney/Gadigal, says many homeowners don’t realise they are underinsured. That matters because, for most people, a home is their biggest financial asset. If the cover falls short, the financial shock after a major event can be severe.
Survey data suggests this is not a niche problem. In an Australia Institute poll conducted last year, 15 per cent of homeowners surveyed said their home was underinsured. Consumer group Choice also notes that many people would struggle to say with confidence whether they are adequately covered, even if they have a policy in place.
What “underinsured” actually means in practice
The government’s MoneySmart guidance defines underinsurance plainly: if your home is underinsured, your insurance policy won’t fully cover the cost of rebuilding, repairing or replacing it. Home insurance typically covers damage or loss caused by events such as natural disasters, theft and accidents. But the existence of cover does not automatically mean the amount of cover is enough.
The key figure is the maximum amount an insurer will pay under a home or home and contents insurance claim—the “sum insured”. To be effective, that amount should not be less than the potential costs you might face after a serious loss.
The Insurance Council of Australia describes the concept in similar terms: underinsurance occurs when a home insurance policy’s sum insured falls short of what it would actually cost to repair and rebuild a property. That difference—between what you’re insured for and what it would cost to restore your home—can become your responsibility.
Why being underinsured can leave you paying more than you expect
One reason underinsurance can be so financially painful is that some policies include clauses that can reduce claim payouts when the sum insured is too low. MoneySmart points to “coinsurance” or “averaging” clauses as an example. These clauses can limit the insurer’s liability on claims to the proportion of the replacement value that has been insured.
MoneySmart provides an illustration of how this can work. Under a coinsurance clause, if you’re insured for only 67 per cent of your home’s value—meaning you are underinsured by 33 per cent—the insurer might only pay 67 per cent of the amount you are insured for if the home was destroyed. In other words, the impact of underinsurance may not be limited to a shortfall against the true rebuild cost; the claim payment itself may be reduced depending on the policy terms.
This is why understanding your policy wording matters. The sum insured is not just a number on a renewal notice; it can influence how a claim is calculated and how much financial risk you carry.
Why underinsurance is becoming more common
Industry groups say the underinsurance problem is being worsened by factors outside the insurance sector. The Insurance Council of Australia notes that construction costs have risen more than 40 per cent since 2020. That rise means some homeowners’ cover may no longer reflect current rebuild costs, even if the sum insured seemed reasonable a few years ago.
MoneySmart describes home and contents underinsurance as “very common” in Australia and warns that it “can creep up on you”. One reason is that policies can end up reflecting an “outdated value” rather than the price of replacing what you have today.
Daniel Graham, an insurance expert with Choice, says underinsurance is mostly caused by home and contents not being insured at replacement cost. Replacement cost is the amount it would cost to replace everything new at today’s price. If your cover is based on older estimates, or if you haven’t revisited your contents value for years, the gap between insured amounts and real costs can widen quietly over time.
Dr Huang also points to broader pressure on household budgets. Rising premiums and inflation have likely left more people underinsured, as some households may respond by reducing cover or letting sums insured fall behind actual rebuild costs.
How underinsurance can change your recovery after a major loss
The biggest risk, according to Mr Graham, is a total loss where you need to rebuild. In that situation, if the insurer determines the amount you’ve insured your building for isn’t enough to replace everything new, you may be offered a cash settlement. That can leave you organising construction yourself while also being substantially out of pocket.
Dr Huang says if an underinsured home is destroyed, owners will likely have to rebuild to a lower standard. Mr Graham outlines other difficult outcomes that may follow from a large shortfall: you might need to reduce the size or standard of your home, or sell the land and buy in a more affordable area.
These scenarios highlight a practical point: underinsurance doesn’t just affect the final dollars and cents. It can shape the choices available to you after a disaster—how quickly you can recover, what you can rebuild, and whether you can remain in the same location.
Common ways people end up underinsured
Underinsurance can happen for multiple reasons, and not all of them involve consciously choosing a lower sum insured. Based on the expert commentary and consumer guidance, several patterns appear frequently:
Cover based on outdated values: A sum insured set years ago may not reflect today’s construction costs or replacement prices.
Not insuring at replacement cost: If your building or contents cover doesn’t reflect the cost of replacing items new at today’s prices, the gap can be substantial.
Having building cover but no contents cover: Some households insure the structure but leave belongings uninsured.
Not being covered for specific scenarios: Some policyholders may be uninsured for particular events such as flood or fire, depending on the policy.
Renovations and additions not reflected in the policy: Improvements can increase rebuild costs and the value of contents, but the sum insured may not be updated.
Even when a policy renews automatically, your circumstances and the cost environment can change significantly. That is why underinsurance can “creep up” rather than arriving as a single obvious mistake.
When to review your sum insured and contents cover
The Insurance Council of Australia recommends reviewing the amount your home is insured for annually and always after renovations. That advice reflects how quickly rebuild costs can shift and how easily home improvements can change the financial stakes.
Mr Graham suggests reassessing home and contents insurance at least every few years, but ideally when your renewal notice arrives. Renovations and additions should be part of that check. Even a change such as installing air conditioning can affect replacement costs and should prompt you to revisit what you are insuring and for how much.
Dr Huang adds another timing consideration: when you’re looking to buy a home, it can be wise to check insurance costs early. In high-risk areas, insurance may be a significant expense, and understanding that cost can help you plan your budget more realistically.
Tools and methods to estimate the right level of cover
Calculating the right sum insured can feel daunting, but there are practical tools and straightforward approaches that can help.
The Insurance Council of Australia recommends using your insurer’s online rebuild calculator and ensuring your policy accounts for demolition, professional fees, and current building code compliance. It also advises speaking to your insurer or broker if you have any doubt.
For contents insurance, Mr Graham recommends a simple, methodical approach: go from room to room and list items. It’s easy to focus on big-ticket items such as furniture and appliances, but smaller things can add up, including clothing. The goal is to arrive at a realistic replacement-cost estimate rather than a rough guess.
Both Mr Graham and Dr Huang recommend using the online calculator tools insurers provide. Mr Graham’s view is that these tools are worth checking, but they should be paired with your own assessment of your possessions and property and how much it might cost to replace them.
Is there any upside to being underinsured to save on premiums?
With home insurance premiums continuing to rise—especially for properties in natural disaster-prone areas—some households may wonder whether accepting a lower sum insured is a way to keep costs manageable.
However, both Mr Graham and Dr Huang argue that the trade-off is not worth the risk. Dr Huang says that unless you are very wealthy, you probably cannot absorb the losses that home insurance is designed to protect against. Mr Graham puts it more bluntly: being underinsured “really goes against the point of the product”.
The underlying issue is that the savings from a lower premium may look appealing in the short term, but the financial consequences of a major loss can be far larger than the premium difference.
Practical ways to lower premiums without cutting essential cover
If the aim is to reduce premiums, the experts suggest focusing on shopping around and adjusting settings that don’t undermine the basic purpose of the policy.
When your renewal notice arrives, Mr Graham recommends spending an hour or two on a weekend getting quotes from different providers. He suggests aiming for at least four or five quotes, and notes that using an independent comparison website can help. He also says there is a huge range in insurance prices, which means time spent comparing can translate into meaningful savings.
Another lever is the excess—the amount you pay out of pocket when you make a claim. Mr Graham says increasing your excess can bring a substantial premium down to something more reasonable. The right excess level will depend on what you could comfortably pay if you needed to claim, but the broader point is that there are options other than reducing the sum insured.
Dr Huang agrees that comparing quotes and swapping between providers can help you get a lower premium in the Australian market. And if you are struggling to get insurance, Mr Graham says it could be worth talking to an insurance broker.
A checklist for reviewing your cover
For homeowners who want to reduce the risk of underinsurance, the guidance from consumer and industry experts can be summarised into a simple review routine:
Check whether your sum insured reflects current rebuild costs, not an older estimate.
Use an online rebuild calculator and ensure your estimate includes demolition, professional fees, and building code compliance.
Review cover annually and after renovations or additions.
For contents, do a room-by-room inventory and think in terms of replacement cost at today’s prices.
Read your policy for coinsurance/averaging clauses and understand how underinsurance could affect a payout.
When renewal arrives, gather multiple quotes and consider adjusting your excess rather than cutting core cover.
If you are uncertain, speak to your insurer, a broker, or seek independent professional advice.
The bottom line
Underinsurance is often invisible until a claim is made, and by then it may be too late to fix. With construction costs rising sharply since 2020 and household budgets under pressure, it is easy for sums insured to fall behind reality. The consequences can be significant: reduced payouts, difficult rebuilding decisions, and major out-of-pocket costs after a disaster.
A regular review—especially at renewal time and after renovations—can help ensure your home and contents are insured at realistic replacement cost. Comparing quotes, using insurer calculators, and understanding key policy clauses can also help you manage premiums without undermining the protection insurance is meant to provide.
This article contains general information only. You should consider obtaining independent professional advice in relation to your particular circumstances.