Just because you owe back taxes does not mean that your credit score will drop. When it comes to dealing with back taxes, it will no longer impact your credit score. If you have been struggling to pay outstanding tax debts, it could be hard to pay other bills that you may have. When you fall behind on other bills, such as car payments or credit card payments, it can negatively impact your credit score. In turn, your tax debt could indirectly affect your credit score based on your situation.