世界各国很多个税是按全家人口平均收入计算的,扣除制度中的扣除项目一般包括成本费用,生计费和个人免税三部分内容。成本费用扣除形式多采用按实列支或在限额内列支的方式。生计费用扣除大多根据赡养人口、已婚未婚、年龄大小等因素进行扣除。个人免税主要是为体现量能、公平的原则而设置的对某些所得给予照顾性的减免项目。美国：五花八门的所得抵扣美国个人所得税的起征点随纳税人申报状态、家庭结构及个人情况的不同而不同,没有统一的标准。美国常规个人所得税共有五种申报状态：单身申报、夫妻联合申报、丧偶家庭申报、夫妻单独申报及户主申报。 A lot of taxes in all countries in the world are calculated on the basis of the average income of the whole family. Deductions in the deduction system generally include three parts: cost and expenses, living expenses and personal tax exemption. The cost of deducting the use of more or less in accordance with the actual expenditure or within the limits of expenditure in the way. Most of the deductions for livelihood expenses are deducted from factors such as the number of dependents, married and unmarried, age and other factors. Personal tax exemption is mainly to give consideration to the amount of energy, fairness and set some of the benefits given to the relief items. The United States: A Variety of Incomes The threshold for the deduction of personal income tax in the United States varies with taxpayers’ declared status, family structure and personal circumstances. There is no uniform standard. There are five types of declarations for routine personal income tax in the United States: single declaration, joint declaration of husband and wife, declaration of widowed families, separate statement of husband and wife and declaration of head of household.