An adverse action is a decision by a creditor, based on a credit score, that causes the creditor to deny a consumer access to credit, or to offer anything less than the best terms available. Federal rules went into effect in 2011 requiring lenders to give to consumers a detailed explanation of the adverse action. In practice, that has meant if consumers are denied credit or given less than the best terms, the lender makes available a free copy of the credit score that triggered the decision.