Assembly is not enough.

It’s not just a tariff, and it’s also not just a single row list of tariffs on countries or products or whatever.

The tariff tables are multi dimensional. Each product has it’s own table of rates. Besides country and product type, there’s a dimension of how it’s assembled/manufactorered and potentially if it’s part of some sort of special agreements etc.

“The tariff” is basically a worldwide database of product information.

There are actually very few products that are fully produced in any one country. This is mostly agricultural or raw ressources. All other products are said to be manufactorered from different countries. The country of origin in that case is the last country in which the product significantly changed value from being manufactorered locally and it requires a facility to do so. Slapping a sticker on something is not enough.

Anyway, the tariff tables take all that into account. It’s very naive to think you can legally bypass this system simply by leaving a product in your neighbors garden before bringing it home.

You don’t have to waste your time doing that for fun. Plenty of people in logistics get paid well for doing just that, and if they can’t find the loophole, there is very little chance that you’ll find it described online.

Country of origin.