A car insurance deductible is the amount that you agree to pay to cover the damage caused by a car accident before your insurance company pays the rest. If you get into a car accident that causes $3000 worth in damages and your deductible if $500 then you pay $500 to cover the costs of the accident and your insurance company pays $2500. As a general rule, the higher the deducible that you choose, the lower your monthly auto insurance payment will be. Only purchase a deductible that fits with your budget and that gives you enough coverage in case of an accident.