You are right, Baron.
Article I, Section 8, Clause 1
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;
http://www.usconstitution.net/xconst_A1Sec8.html
Embellished in 16th Amendment
Passed by Congress July 2, 1909
Ratified February 3, 1913