What it means
Most liability policies carry two ceilings rather than one. The per occurrence limit answers the question of how much one bad event can cost the insurer, and the aggregate limit answers how much a whole bad year can cost.
A policy quoted as one million on two million means one million for any single claim and two million in total for the twelve months. The reason insurers use an aggregate is straightforward risk control.
Without one, a business with a systematic problem, say a defective component fitted to thousands of units, could generate an unlimited series of individually modest claims. The aggregate converts an open ended exposure into a number the insurer can price and reserve against.
For the business buying cover, the aggregate is the figure that determines what happens after the first bad claim. Many buyers focus entirely on the per occurrence number and never notice that a single large settlement has consumed most of the year's total capacity.
From that point the company is effectively self insuring for anything else that happens before renewal. Not every aggregate works the same way.
General liability policies often carry a general aggregate plus a separate, lower products and completed operations aggregate, while professional indemnity cover is frequently written so that defence costs erode the limit rather than sitting on top of it. Reading which costs count towards the aggregate is more important than the headline number.
The practical response is to buy an excess layer or to negotiate reinstatement. An excess policy sits above the primary one and picks up claims once the primary aggregate is exhausted, while a reinstatement provision restores the limit, usually once and usually for an additional premium.
Both cost money, so the choice depends on how likely multiple claims are in the same year.
In practice
Real-world examples.
Example
A medical devices distributor faces nine separate claims in one year from a batch of faulty pressure cuffs, each settling between $80,000 and $200,000. No single claim comes near the per occurrence limit, yet together they exhaust the products aggregate by October and leave the company uninsured for the final quarter.
Example
An architecture practice discovers that its professional indemnity policy counts legal defence costs against the aggregate. Two years of defending a disputed claim consume $400,000 in fees before any settlement, reducing the cover available for a second, unrelated dispute.
Example
A logistics company buys a $5,000,000 excess liability layer above a primary policy with a $2,000,000 aggregate. When a warehouse fire and a separate vehicle accident together exhaust the primary limit, the excess layer responds to the remainder rather than the company funding it from cash reserves.
Think of it
“Aggregate limit is the total cap for the year-maximum across all claims combined.
Formula
Calculation
Remaining aggregate limit = aggregate limit - total claims paid so far in the policy period
A specialist contractor holds a general liability policy with a $1,000,000 per occurrence limit and a $2,000,000 aggregate limit for the year. In March a site incident settles for $600,000, and in July a second claim settles for $750,000. Claims paid to date are $600,000 + $750,000 = $1,350,000, so the remaining aggregate is $2,000,000 - $1,350,000 = $650,000.
In November a third claim is assessed at $900,000. Even though this is below the $1,000,000 per occurrence limit, the insurer pays only the $650,000 of aggregate that remains, and the contractor funds the balance of $900,000 - $650,000 = $250,000 itself. That $250,000 gap is the direct cost of watching the per occurrence limit while ignoring the aggregate.Case study
Seen in the real world.
This is an illustrative, invented scenario rather than a real case. Harbour Lane Playgrounds, a fictional manufacturer and installer of school play equipment, renewed its liability cover each year on price alone, and in one renewal moved to a cheaper policy whose aggregate limit had dropped from $5,000,000 to $2,000,000 while the per occurrence limit stayed at $1,000,000. The broker had flagged the change in an email, but nobody at the company understood what an aggregate limit governed.
A design fault in a climbing frame joint produced a run of injury claims across fourteen schools over eighteen months. Individually the claims were small, averaging around $150,000, but they arrived in the same policy year and the aggregate was gone before the eleventh claim. The remaining settlements and legal costs, roughly $520,000, came out of the company's own funds during a year when it was already funding a product recall.
In this fictional account the finance director introduced a simple rule afterwards: any policy change to a limit, deductible or exclusion had to be summarised in one page and signed off at board level. The premium saving that had triggered the switch had been $18,000 a year.
Watch out
Common mistakes.
- Reading the per occurrence limit as the amount of cover available and forgetting that the aggregate governs the year as a whole.
- Assuming defence and legal costs sit outside the limit, when many professional indemnity policies let those costs erode it.
- Failing to track claims against the aggregate during the year, so nobody knows how much cover is actually left until a claim is refused.
Questions
People also ask.
Does the aggregate limit reset if I make a claim?
Not automatically; it resets at renewal, and a mid term restoration only happens if the policy contains a reinstatement provision, usually for an extra premium.
Do all insurance policies have an aggregate limit?
No, many property and motor policies work per event without a yearly cap, while liability, professional indemnity and products cover almost always carry one.
How do I decide what aggregate limit to buy?
Estimate a realistic worst year rather than a worst single claim, considering whether one underlying fault in your product or process could generate several claims at once.
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