No Claims Bonus is a term used to describe the number of years you have had Car Insurance without making a claim. Put simply, if you have had Car Insurance for 4 years and you have not made a claim in that time, then you have 4 years No Claims Bonus. No Claim Bonus is probably the single biggest factor affecting the cost of your Car Insurance premium. Every year that goes by without you making a claim is another year of No Claims Bonus. Generally speaking, the more No Claims Bonus years you have, the cheaper your premium will be for the car you need to insure. This is because Car Insurance companies can see that your history regarding making any claims is a good one. When changing provider, Car Insurance companies will usually ask you to prove your No Claims Bonus in the form of a renewal notice or a letter from your current Car Insurance company. If you have several years of No Claims Bonus but then make a claim, the Car Insurance company will usually apply it's rules of how much to knock back your No Claims Bonus Years. Some companies offer to protect your No Claims Bonus for an extra fee during the quotation process. Having full no claims bonus can also entitle you up to 75% discount on your car insurance premium.