| Art. I., § 8, cl. 1 | General Welfare Clause | The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; |
| Art. I., § 2, cl. 3 | Direct-Tax Apportionment Clause | Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons. |
| Art. I., § 7, cl. 1 | Origination Clause | All bills for raising revenue shall originate in the House of Representatives; but the Senate may propose or concur with amendments as on other Bills. |
| Art. I., § 9, cl. 4 | Apportionment Clause | No Capitation, or other direct, Tax shall be laid, unless in Proportion to the Census or Enumeration herein before directed to be taken. |
| Art. I., § 8, cl. 1 | Uniformity Clause | [The Congress shall have Power To lay and collect Taxes . . ] but all Duties, Imposts and Excises shall be uniform throughout the United States. |
| Art. I., § 8, cl. 3 | Commerce Clause | To regulate commerce with foreign nations, and among the several states, and with the Indian tribes |
| Amend. XIV | Income Tax Amendment | The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration. |