[Paleo Conservative]

Why would the 16th Amendment need to be repealed in order for the government to pass a law that it no longer would assess an income tax?

Because a future congress could repeal that legislation and re-institute an income tax.

[fightinJAG]

That’s a separate issue from whether or not Congress has the power to go ahead and eliminate the income tax.

It does.

These two actions can be pursued concurrently.