Now it should go without saying that paying your bills on time is a critical factor in keeping your score high. It accounts for 35% of your score. If you have a high credit score such as 800, or over your score could down could go down by 125 points just for overlooking one bill. If your score is at 600, your score might go down 25 to 30 points, the better your score is the more deleterious effect a bad action has