Most insurance companies for the tortfeasor (the person, persons or company who caused your injuries) will not automatically pay medical bills as they occur. There are many reasons for this. One reason is that they do not want to spend a substantial amount of money for medical bills and then be faced with an unreasonable or excessive demand at the time of final settlement. In other words, they do not want to expend a substantial sum of money on medical bills and then be faced with the chance of defending a lawsuit. Secondly, most insurance companies want to conclude or settle the claim with one sum of money. Therefore, most liability insurance companies will wait for the letter of demand from your attorney and then try to conclude the case all at once with one payment.