Retrospectively rated insurance is a method of establishing a premium on large commercial accounts. The final premium is based on the insured's actual loss experience during the policy term, sometimes subject to a minimum and maximum premium, with the final premium determined by a formula. Under this plan, the current year's premium is based partially (or wholly) on the current year's losses, although the premium adjustments may take months or years beyond the current year's expiration date. The rating formula is guaranteed in the insurance contract. Formula: retrospective premium = converted loss + basic premium × tax multiplier. Numerous variations of this formula have been developed and are in use.
The cheapest car insurance, period, will likely carry the minimum coverage required in your state. In most states, this is liability insurance only, which covers property damage and medical bills for others due to accidents you cause. Some states also require uninsured and underinsured motorist coverage, which pay for your injuries or damage if an at-fault driver doesn’t have enough insurance.