People often build up bad credit when they have problems repaying money they have borrowed. For example, if you miss payments, have CCJs or have been declared bankrupt you may find that your credit score has been negatively affected. Lenders are more likely to reject applications from customers with a low credit score because there is a greater risk that they won’t be able to keep up with repayments. Alternatively if you have never held any previous credit agreements, or not registered to vote etc, this can also keep your score low.