An insurer's largest liability is an estimate. Claims reported today may take years to settle, and the figure held against them determines what the business reports and how it prices.
Why the cost is unknown at the time of the claim
Some claims settle within days for a known amount. Others involve injury, litigation or damage whose full extent emerges gradually.
Until the matter closes, the insurer holds a reserve representing its best estimate of the eventual payment, and that estimate is revised as information arrives.
There is also a category of claims that have occurred but have not yet been reported, which must be estimated statistically from patterns in previous years.
Reserves determine reported profit
Profit for a period is calculated after deducting the change in reserves, so the estimate directly sets the reported result.
Strengthening reserves reduces current profit, while releasing reserves that prove excessive increases it, sometimes years after the business was written.
This means a substantial part of reported earnings in the sector reflects revisions to old estimates rather than the performance of current underwriting.
The estimate feeds directly into pricing
Prices are set against expected claims cost, and the primary evidence for that cost is what previous years have turned out to cost.
If reserves prove too low, the underlying claims trend was worse than assumed, which implies current prices are also too low and must rise.
Because this discovery takes years, pricing corrections arrive late and then move sharply, which is one of the drivers of cycles in insurance markets.
Inflation affects reserves after they are set
A reserve set today may be paid out several years later at prices prevailing then, particularly where the cost is repairs, medical treatment or legal work.
Cost increases in those specific areas can differ substantially from general price measures, which is what makes long-tail lines difficult to reserve.
An extended period of rising costs erodes reserves set under different assumptions, and the shortfall appears gradually rather than all at once.
Why regulators examine the assumptions
Because the estimate is judgemental, it could be used to smooth reported results, presenting a steadier picture than the underlying business supports.
Supervisors therefore require independent actuarial review and disclosure of how reserves have developed against original estimates over time.
That development history is the most informative disclosure an insurer makes, since it shows whether past estimates were systematically optimistic or cautious.