A subassembly classifies as a part under 8473 when it is identifiable as suitable for use solely or principally with ADP machines and lacks the functional completeness to be classified as a machine in its own right. CBP has issued numerous rulings on this boundary — particularly for storage devices, interface cards, and power supplies — and importers should review applicable rulings or seek a binding ruling for novel configurations.

Section 301 tariffs under the current lists apply specifically to goods of Chinese origin. Parts manufactured in Vietnam and properly documented as Vietnamese-origin are not subject to Section 301, though CBP scrutinizes country-of-origin claims in electronics supply chains closely, particularly where Chinese components undergo further processing in third countries.