Since the United States declared its Independence September 17, 1776, it has never had a permanent income tax until 137 years later when the 16th Amendment was enacted in February 3rd, 1913. The federal government received more than enough revenue to operate with Duties, Imposts and Excise taxes to pay its debts and provide for common defense. On only a few occasions did the federal government enact a temporary tax on income but they either had a sunset clause or were otherwise immediately removed.

Some people argue that the 16th Amendment was passed illegally or not ratified properly. My endeavor is to pull together the best information available. As always, do your own homework.
What does the Constitution say?

Article 1, Section 2, Clause 3 (Ratified, January 10, 1791)
"Representatives and direct taxes shall be apportioned among the several States which may be included with 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 Indian not taxed, three fifths of all other Persons.
Article 1, Section 8, Clause 1 (Ratified, January 10, 1791)
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; but all Duties, Imposts and Excises shall be uniform throughout the United States;
Article 1, Section 9, Clause 1 (Ratified, January 10, 1791)
"The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by Congress prior to the Year one thousand eight hundred and eight, but a Tax or duty may be imposed on such Importation not exceeding ten dollars for each Person."
Article 1, Section 9, Clause 4 (Ratified, January 10, 1791)
"No Capitation, or other direct, Tax shall be laid, unless in Proportion to the Census or enumeration herein before directed to be taken."
Article 1, Section 9, Clause 5 (Ratified, January 10, 1791)
"No Tax or Duty shall be laid on Articles exported from any State."
Amendment 14, Section 2 (Ratified, July 9, 1868)
"Representatives shall be apportioned among the several States according to their numbers, counting the whole number of persons in each State, excluding Indians not taxed. But when the right to vote at any election for the choice of electors for President and Vice President of the United States, Representatives in Congress, the Executive and Judicial officers of a State, or members of the Legislature thereof, is denied to any of the male inhabitants of such State, being twenty-one years of age, and citizens of the United States, or in any way abridged, except for participation in rebellion, or other crime, the basis of representation therein shall be reduced in proportion which the number of such male citizens shall bear to the whole number of male citizens twenty-one years of age in such State."





Amendment 16  (Ratified, February 3, 1913)
"The Congress shall have the 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."
The passage of the 16th Amendment is highly controversial and much has been written about it. I will endeavor to bring the relevant arguments together here for your consideration.As always, do your own homework.

Amendment 24  (Ratified, January 23, 1964)
"The right of citizens of the United States to vote in any primary or other election for President or Vice President, for electors for President or Vice President, or for Senator or Representative in Congress, shall not be denied or abridged by the United States or any State by reason of failure to pay poll tax or other tax. The Congress shall have power to enforce this article by appropriate legislation."