We did get it right the first time, in Article I, Section 9, Clause 4 (Scroll down) of the Constitution, but unfortunately the 16th Amendment put an end to that.
Prior to the amendment, income taxes were, in fact illegal, as decided by Pollock v. Farmers’ Loan & Trust Co. (1895), in which the justices declared that taxes on certain kinds of income (real estate, bonds) were certainly illegal. They withheld judgment on whether other types of income taxes were unconstitutional or whether they would be rendered unconstitutional by being non-uniform on the grounds that those issues were not pertinent to the case in question.
