An obligation is an action one owes one or more other people. When one fulfills an obligation one does something good but not all good actions are obligations. Some actions are supererogatory , they go above and beyond obligation. I am obliged to pay taxes but I am not obliged to donate money to charity. Both actions are good but the latter is a supererogatory action. The moral status of an action depends on whether the action is an obligation. Failure to perform an obligatory action is wrong. The value of an action does not so depend. An action can be good even if it is not obligatory. It is good to give a present to someone; it is not an obligation. Some obligations are performed willingly, others not. If one does not desire to perform a supererogatory action and does not perform it, then one has committed no wrong. If one does not desire to perform an obligatory action, and does not perform it, then one commits a wrongful omission. If you don't pay your taxes, then you r...