Abstract U.S. automotive and auto parts manufacturers face rising complexity from tariff stacking, especially after the August 2025 expansion of Section 232 duties to hundreds of additional product codes. Importers must now separate and report the value of embedded metals while also applying other tariffs on non-metal content. This paper highlights the limits of relying on suppliers, the chance to use existing procurement data, and the need for cross-functional processes to withstand closer scrutiny from U.S. Customs and Border Protection (CBP).
Automotive and auto parts manufacturers must now separate the value of metal content from overall customs value more carefully than ever before. The Bureau of Industry and Security’s August 2025 rule expanded Section 232 coverage to hundreds of additional product codes, many of them tied to automotive supply chains. That expansion means even parts not primarily metallic can trigger a 50% tariff on embedded steel or aluminum. Importers must therefore examine each component’s composition and document it in detail.
The expanded coverage has made disclosure and segregation of content more difficult. Products once treated as finished goods now require deeper analysis to determine their underlying materials. A part that combines steel, aluminum, copper, and plastics can be subject to multiple tariffs at once. This complexity turns tariff filing into a compliance risk if not managed carefully.
Depending only on suppliers for material breakdowns is no longer sufficient. Suppliers may hesitate to share proprietary costing data or may not classify materials consistently. Importers that rely on incomplete or inaccurate supplier information risk under-reporting or misclassification. In this environment, companies must verify and supplement supplier data with their own internal resources.
The good news is that companies already hold much of the information needed to meet these obligations. Procurement and purchasing departments track unit costs, material inputs, and sourcing data, which can be adapted for customs valuation purposes. By using these records, importers can build a defensible approach to tariff allocation without relying solely on external suppliers. What is essential is a cross-functional effort—bringing together procurement, compliance, accounting, and supply chain teams—since in most goods the relevant cost and material information is already available internally.
Looking ahead, CBP is expected to apply stricter standards to test the accuracy of importers’ declarations. Companies should assume that content-based filings will be challenged and that well-documented support will be required. Transparent and consistent processes linking customs and purchasing practices are the best defense. In this environment, tariff compliance becomes a cross-functional responsibility and a strategic requirement for competitiveness.