The no-claims bonus is a legal indicator common to all insurers that allows the car insurance premium to be adapted to the driving behaviour of the policyholder at each annual due date.
The idea is to make drivers who cause claims responsible by increasing their contribution and, conversely, to reward the prudence of motorists who have not caused claims by reducing their premium.
A claims-free year thus allows you to increase your bonus and thus reduce your insurance premium. On the contrary, being responsible for a claim inflicts a penalty on you and can cause your premium to increase.
For more details, you can click on this link.