Compulsory insurance laws require that every person who registers a motor vehicle in a given state prove or certify that he carries liability insurance equal to at least the state minimum requirements. The laws of all states express this requirement in terms of split limits. For example, if the chart shows "25/50/10," the law requires that the policy provide at least $25,000 for bodily injury to each person, $50,000 for all bodily injury, and $10,000 for property damage for each accident.

The insurance laws of some states also state the requirement in terms of a combined single limit. For example, if the chart shows "15/30/10 or 40," the law provides that a policy with a combined single limit of at least $40,000 will also satisfy the requirement. A combined single limit of $40,000 means that the insurance will pay up to $40,000 for all bodily injury and property damage arising out of each accident.