Your contract with your Insurance Company requires you to ‘promptly’ report any accidents you are involved in, whether it was your fault or non fault. It is in the terms and conditions of the policy that you confirmed you had read when you ticked the box. I know….who really reads the T&Cs!? but you really should do when it comes to car Insurance as there are a LOT of public misconceptions.
The reason the Insurance Company wants to know of any accidents is that when they calculate the cost of your policy they are actually calculating the ‘risk’ of Insuring you (how much you pay them against who much they may have to pay out). Obviously someone who never has any accidents will be considered a lower risk than someone who does. However something that is not widely known/realised:
Your Insurance Company will count a claim against you where you were at fault even if you settle the claim privately.

Many people think if they pay themselves the insurer will not put their policy up, this is incorrect, the policyholder is now seen as a higher risk even though it did not cost the Insurer a penny. If the Insurer does not pay anything then your No Claims Bonus is not affected but No Claims Bonus is applied AFTER the policy risk has been calculated – so the base policy cost goes up and then the NCB is applied. So basically there is no point settling a claim privately if your Insurer knows about the claim – they will increase the cost of your policy up by the same amount regardless.

You also need to provide your Insurance Company with any information you have about the incident including the Third Party details (this is also in the Terms & Conditions) as sometimes delaying this can mean you are increasing the cost of the claim for your Insurer by not giving them the means to deal with the Third Party quickly, the Third Party could be directed to an Accident Management Company who can increase the cost of the claim legitimately with hire cars and Injury solicitors etc. In some cases an Insurer will refuse to deal with your claim if they feel you have increased the cost of a clam by refusing to pass on vital details in the hope that it will ‘go away’.