[ancient_geezer]

True a state may not lay a tax on federal purchases, as that would violate federal authority.

That does not however prevent the federal government from taxing its own entities.

This is a Federal tax, taxing consumption of its own Federal agencies. There is no violation of State autonomy by the Federal authority, nor Federal autonomy by a state authority.

[lewislynn]

This is a Federal tax, taxing consumption of its own Federal agencies.

As usual, wrong again. There are no exemptions...remember?

`(a) GOVERNMENT ENTERPRISES TO COLLECT AND REMIT TAXES ON SALES- Nothing in this subtitle shall be construed to exempt any Federal, State, or local governmental unit or political subdivision (whether or not the State is an administering State) operating a government enterprise from collecting and remitting tax imposed by this subtitle on any sale of taxable property or services. ....

BTW, where does the federal government get the money to pay itself taxes?... That, and the sales(?) tax on "any government" wages sure shoots a hole in the "You make your choices as to how much tax you pay by how much you buy", theory doesn't it?