Each company adopts its own rating system, although there are general guidelines that all companies follow.
The single greatest influence on the rating process is claim frequency. This does not mean how many times you specifically have made an insurance claim, although that will have an additional effect. Claim frequency measures how often an insured event occurs within a group relative to the number of policies contained in that group. Persons sharing characteristics with high claims groups will be charged more for insurance coverage.
Your driving record – drivers with previous violations or accidents are considered to be higher risk
Your geographic territory – urban areas have more claims than rural areas
Your gender and age – males have more accidents; certain age groups have more claims
Your marital status – married people show lower rates of claims
Prior insurance coverage – if you have been cancelled for non-payment of premiums
Vehicle use – higher annual mileage results in higher exposure to risk
Make and model of your vehicle – luxury and sports cars average a higher number of claims