Supererogation (Late Latin: supererogatio "payment beyond what is due or asked", from super "beyond" and erogare "to pay out, expend" [from ex "out" and rogare "to ask"]) is the performance of more than is asked for; the action of doing more than duty requires. In ethics, an act is supererogatory if it is good but not morally required to be done. It refers to an act that is more than necessary, when another course of action—involving less—would still be an acceptable action. It differs from a duty (which is an act that would be wrong not to do), and from acts that are morally neutral. Supererogation may be considered as performing above and beyond a normative course of duty to further benefits and functionality.
In the theology of the Roman Catholic Church, "works of supererogation" (also called "acts of supererogation") are those performed beyond what God requires. For example, in 1 Corinthians 7, Saint Paul says that while everyone is free to marry, it is better to refrain from marriage and remain celibate to better serve God. The Roman Catholic Church holds that the counsels of perfection are supererogatory acts, which specific Christians may engage in above their moral duties. Similarly, it teaches that to determine how to act, one must engage in reasonable efforts to be sure of what the right actions are; after the reasonable action, the person is in a state of invincible ignorance and guiltless of wrongdoing, but to undertake more than reasonable actions to overcome ignorance is supererogatory, and praiseworthy.
According to the classic teaching on indulgences, the works of supererogation performed by all the saints form a treasure with God that the Church can apply to exempt repentant sinners from the works of penitence that would otherwise be required of them to achieve full reconciliation with the Church.
Opposition to and the abuse of this teaching was the main point of Martin Luther when he began opposing the Catholic Church, and thus a seed of the Protestant Reformation as a whole. The Anglican Church denied the doctrine of supererogation in the fourteenth of the Thirty-Nine Articles, which states that works of supererogation
"cannot be taught without arrogancy and impiety: for by them men do declare, that they not only render unto God as much as they are bound to, but that they do more for his sake, than of bounden duty is required: whereas Christ saith plainly, When ye have done all that are commanded to you, say, We are unprofitable servants"
Many later Protestant movements followed suit, e.g. in the Methodist Articles of Religion.
A Muslim must complete a minimum of the 5 daily prayers, each typically lasting an average of 5 to 10 minutes. Supererogatory prayers beyond these are known as nafl prayers, and praying them are considered to bear additional reward. There are also several other supererogatory acts in Islam, such as fasting outside of the month of Ramadhan, or giving sadaqah (charity, consisting of simple acts of kindness to financial assistance) that is not obligatory.
Whether an act is supererogatory or obligatory can be debated. In many schools of thought, donating money to charity is supererogatory. In other schools of thought that regard some level of charitable donation to be duty (such as with the tithe in Judaism, zakat in Islam, and similar standards in many Christian sects), only exceeding a certain level of donation (e.g. going above the common 2.5%-of-capital-assets standard in zakat) would count as supererogatory.
In criminal law, it may be observed that state prohibitions on killing, stealing, and so on derive from the state's duty to protect one's own citizens. However, a nation state has no duty to protect the citizens of an adjacent nation from crime. To send a peacekeeping force into another country would be — in the view of the nation doing it — supererogatory.
Some schools of ethics do not include supererogatory acts. In utilitarianism, an act can only be better because it would bring more good to a greater number, and in that case it becomes a duty, not a supererogatory act. The lack of a notion of supererogation in utilitarianism and related schools leads to the demandingness objection, arguing that these schools are too ethically demanding, requiring unreasonable acts.