What BAA says:
The Buy American Act of 1933 (BAA) applies when the US federal government is purchasing goods or services (construction) for its own use and such purchases exceed the micro-purchase threshold (currently $10,000) and are below the applicable dollar threshold for Trade Agreements Act applicability. The BAA restricts the Federal government from purchasing non-domestic goods by establishing a preference for “domestic end products” and “domestic construction materials.” What qualifies as “domestic” under the BAA differs depending on whether the applicable manufactured end product or construction material consists wholly or predominantly of iron or steel or a combination of both.
With respect to items that do not consist wholly or predominantly of iron or steel or a combination of both, the BAA applies a two-part test. The item must be “manufactured” in the US and either: (a) the cost of its components mined, produced, or manufactured in the US exceeds 65% of the cost of all its components, or (b) it is a commercially available off-the-shelf (COTS) item. In other words, a COTS item that is manufactured in the US is considered domestic regardless of the percentage of domestic components in such item. Note that the 65% domestic content requirement applicable to non-COTS items is scheduled to increase to 75% in 2029.
With respect to items that do consist wholly or predominantly of iron or steel or a combination of both, the BAA also applies a two-part test. The item must be “manufactured” in the US and the cost of foreign iron and steel must constitute less than 5% of the cost of all the components used in the end product.