所得税（英语：Income Tax，香港称「入息税」，日本、韩国和**称「所得税」），是税种之一类，按自然人、公司或者法人为课税单位。世界各地有不同的课税率系统，例如有累进税率（en:progressive tax）也有单一平税率多种。

有些国家或地区以公司为课税的称作企业税，这经常被称为公司税，或公司收入税，或营利事业综合所得税。有些国家或地区以个人收入课税的。个人所得税为法律规定，自然人应向政府上缴的收入的一部分。各地政府在不同时期对个人应纳税收入的定义和征收的百分比不尽相同，有时还分稿费收入、工资收入以及偶然所得（例如彩票中奖）等等情况分别纳税。目前全世界中仅只有卡塔尔和巴林没有征收所谓的所得税。

An income tax is a government levy (tax) imposed on individuals or entities (taxpayers) that varies with the income or profits (taxable income) of the taxpayer. Details vary widely by jurisdiction. Many jurisdictions refer to income tax on business entities as companies tax or corporate tax. Partnerships generally are not taxed; rather, the partners are taxed on their share of partnership items. Tax may be imposed by both a country and subdivisions. Most jurisdictions exempt locally organized charitable organizations from tax.