It is a sales tax, they're just pretending that it will be paid by the seller--as though corps will just take a 3% hit on profit margin! The only differences I can see are A) the tax will be obfuscated (i.e. baked into the sales price, or shifted from low-margin to high-margin items), rather than neatly listed as a line item on the receipt, and B) businesses with revenue under 25M are exempt.

Sales taxes are typically a geographic boundary and a product inclusion/exclusion list. The addition of “seller’s annual revenue” may not fit within existing legal definitions (I haven’t checked), and I expect that naming it a “corporate tax” serves various marketing purposes (both for the headline’s author, and for the proposal’s authors).

The tax should be on sales I think. You can't move out the customers.