A tax collected at the border
A tariff is a tax on imported goods. Strip away the politics and that is all it is: when a product crosses the border into a country, the government charges a percentage of its value, and that money goes to the national treasury.
The mechanics are precise and worth getting exactly right, because the whole subject is misunderstood at this first step. The tax is paid by the importer of record, the domestic company bringing the goods in, at the moment they clear customs. If a retailer in Country A imports a shipment worth 1 million dollars under a 25 percent tariff, that retailer writes the government a check for 250,000 dollars to release its own goods.
Notice who did not pay: the foreign country, and the foreign manufacturer, sent no money to anyone's treasury. The phrase "we are charging that country a tariff" is, mechanically, false. The check is written by a domestic importer to its own government.
That single fact, who physically pays, is where the real question begins: not who hands over the money, but who ultimately bears the cost.

