Every motor policy carries an excess, the amount the policyholder pays before the insurer contributes. Raising or lowering it changes the premium considerably, and the mechanism is worth understanding.
Small claims are disproportionately expensive to handle
Every claim requires notification, assessment, an estimate, authorisation and settlement, and that administrative work costs a similar amount regardless of the sum involved.
On a large claim those costs are trivial as a proportion. On a small one they can approach the value of the repair itself.
An excess removes the smallest claims from the system entirely, and the saving to the insurer is larger than the value of the claims removed.
It changes behaviour as well as arithmetic
A policyholder facing an excess weighs whether claiming is worthwhile, and many minor incidents are settled privately or simply left unrepaired.
That reduces claim frequency beyond what the excess amount alone would suggest, an effect insurers rely on when pricing the option.
The same reasoning explains why the discount for a higher excess grows less than proportionally: most of the benefit is captured at modest levels.
Compulsory and voluntary amounts stack
Insurers impose a compulsory excess reflecting the risk profile, and this can be raised for inexperienced drivers or for particular vehicle types.
A voluntary excess is chosen by the policyholder in exchange for a lower premium, and the two are added together when a claim is settled.
The total is what matters at the point of claim, and policyholders are frequently surprised by the combined figure because only the voluntary part was a conscious decision.
Some claims are treated differently
Glass cover often carries its own separate excess, usually lower for a repair than for a replacement, which is intended to encourage repair where it is possible.
Claims where another party is clearly responsible may see the excess recovered along with the rest of the costs, though the policyholder pays it initially.
Policy wordings vary substantially in these details, and jurisdictions differ in what is permitted, so the specific document governs rather than any general rule.
The trade-off is a cash flow question
Choosing a higher excess means accepting a known, larger cost at an unpredictable moment in exchange for a certain, smaller saving each year.
The decision therefore depends on whether the excess amount could be paid without difficulty at short notice, which is a matter of circumstance rather than arithmetic.
It also depends on claim frequency, since a driver who claims rarely captures the saving repeatedly while a driver who claims often pays the higher excess each time.