Underinsurance means the sum insured on a policy is lower than what it would actually cost to rebuild, replace or recover. It is discovered at claim time, when the payout is calculated against the true value rather than the figure on the schedule. Fixing it is arithmetic, not luck: price the rebuild rather than the market value, price stock and plant at replacement cost today, set an indemnity period long enough to trade back, then review the numbers every year.
What underinsurance looks like in practice
Almost nobody underinsures on purpose. It happens quietly, in three ways. A figure was set when the property was bought and rolled forward at renewal for years while building costs moved. A business grew, added plant and stock, and never told the insurer. Or the number was a guess made under time pressure on a renewal form nobody had time to read.
Moneysmart’s guidance on home underinsurance describes the same pattern for households, and the cause is identical for a warehouse or a strip shop. The sum insured stops being a calculation and becomes a habit.
How insurers respond to underinsurance
Sums insured that fall short have two consequences. On a total loss the answer is simple and brutal: the policy pays its limit, and the shortfall is yours. Rebuild a factory that is insured for less than it costs and the gap comes from the business.
The second consequence is less well known. Many property policies carry an average or co-insurance condition. It treats an owner who insured for less than the full value as having chosen to carry part of the risk themselves, so a partial loss is reduced in the same proportion as the shortfall in the sum insured. A fire that damages one section of a building can then be settled well below its repair cost, even though the claim is nowhere near the policy limit. Owners are usually surprised by this, because they assumed a small claim under a large limit would be paid in full.
Average is a condition, not a penalty, and it is disclosed in the product disclosure statement. The point of knowing about it is that it makes accuracy matter on every claim, not just catastrophic ones.
Buildings: rebuild cost, not market value
The price paid for a property and the cost of rebuilding it are different numbers, and they move independently. A building sum insured has to carry the full job:
- Demolition and removal of debris after the loss.
- Rebuilding to current building codes and standards, which are usually stricter than when the place was built.
- Architects, engineers, surveyors and council fees.
- Escalation, because construction cost rises between the day the policy is set and the day the job finishes.
- Anything that is not obviously building: car park, fencing, signage, landscaping, solar, security systems.
For a commercial property, a valuation for insurance purposes is worth the cost on any building of substance and should be refreshed periodically. Our commercial property owner insurance page covers what a landlord needs to hold alongside the building figure. Moneysmart’s guidance on choosing home insurance walks households through the same exercise, and contents should be checked against a home and contents list built room by room.
Business interruption is where the shortfall bites hardest
Property underinsurance is visible. Interruption underinsurance is not, and it is more common. Two numbers decide the outcome.
The first is gross profit as the policy defines it, which is rarely the accountant’s gross profit. Insurers work from turnover less specified variable costs, and the specification is the part businesses get wrong. Uninsured working expenses that were excluded to save premium reappear as a shortfall.
The second is the indemnity period, the length of time the policy will pay for. It has to cover the whole recovery, not the rebuild: demolition, approvals, construction, fit out, refitting plant, then trading back to where the business was. For a manufacturer waiting on imported machinery, or a food business needing council approvals, that is far longer than owners assume. business.gov.au’s guidance on managing business insurance makes the general case for reviewing these figures whenever the business changes. Our business interruption insurance page sets out how the calculation is built.
Stock and plant move faster than anything else
Buildings drift slowly. Stock and plant can be wrong within a single trading year. A business that buys new machinery, takes on a distribution line or holds more inventory than it did last winter has changed its exposure without changing its policy. Declared values on a property policy are a snapshot, and the snapshot ages.
Plant should be insured at what it would cost to buy and install an equivalent item today, including freight, currency movement on imported equipment, and the labour to commission it. Written down book value is an accounting figure and it is almost always lower than replacement cost.
Habits that prevent underinsurance
Sums insured are not a set and forget number. Three habits keep them honest.
- Review annually against something real: a valuation, a builder’s rate, an asset register, the last set of financials. Rolling last year’s figure forward is how the gap opens.
- Tell the insurer when the business changes. New plant, a second site, a bigger stock holding before Christmas, a renovation. Mid term adjustments are routine and cheap.
- Check the seasonal peak, not the average. A retailer or grocer insured for average stock is underinsured for the weeks when a loss would hurt most.
What FRS does: we build the numbers with the client rather than accepting the figure carried over from last year. That means working through rebuild cost, plant and stock at replacement value, the gross profit definition the policy actually uses, and an indemnity period matched to how long recovery would really take. We flag mid term changes and we put the calculation in writing, so if a claim is ever argued the basis is on file.
If your sums insured have not been looked at properly in a few years, that review is where we would start.
Frequently asked questions
How do I know if my building is underinsured?
Compare the sum insured against a current rebuild estimate, not the market value or the purchase price. Include demolition, debris removal, professional fees, compliance with current building standards and cost escalation during the rebuild. If the figure has simply rolled forward at renewal for several years, assume it is short until proven otherwise.
What is an average or co-insurance clause?
It is a policy condition that reduces a partial claim when the sum insured is below the true value. The insurer treats you as having carried part of the risk yourself, so the payout is cut in the same proportion as the shortfall. It applies to ordinary claims, not only total losses.
How long should my indemnity period be?
Long enough to demolish, obtain approvals, rebuild, refit and trade back to where you were. Many businesses hold twelve months and need more, particularly where imported plant, planning permits or a rebuilt customer base are involved. Work it out from your own worst case rather than accepting a default.
Does increasing my sum insured cost much more?
Usually less than owners expect, because the correction is a proportion of an existing premium rather than a new policy. Weigh it against funding the shortfall yourself after a loss. Getting the number right also removes the argument about average, which is the part that damages a partial claim.
