Actually, it doesn't: Congress already had the power to levy income taxes. The power to levy an income tax predates the 16th Amendment. What the 16th Amendment

Actually, it doesn't: Congress already had the power to levy income taxes. The power to levy an income tax predates the 16th Amendment. What the 16th Amendment did was to explicitly overturn the Pollock SCOTUS decision, which said that a tax on rental income is basically a tax on property, and a tax on property is a direct tax which requires specifically apportionment among the states per the Constitution.