U.S. manufacturers and other importers of aluminum, steel and copper now face a new set of rules by which tariffs on the metals are calculated, presenting fresh paperwork requirements, and possibly higher costs, experts say.

Effective April 6, 2026, President Donald Trump imposed a 50% tariff on the full value of semi-finished aluminum, steel or copper products (e.g. raw materials, coils, sheets) and 25% on the full value of aluminum- steel- or copper-intensive derivative products (e.g. appliances, trucks, silverware, trains). The rate is now 10% if at least 95% of the copper, steel and aluminum in the product is U.S.-sourced, and goods are exempt if the metal content is 15% or less by weight. 

Goods covered by Section 232 tariffs, levied on imports determined to be critical to national security, remain exempt from global, temporary tariffs under Section 122 of the Trade Act of 1974.

That means the rate on many products has dropped from 50% to 25%, but the base on which the tariff rate applies is to the entire value of a finished product containing steel, aluminum or copper — not just the value of the metal used to make it, as was previously the case.

The Cato Institute, a libertarian think tank, said the change will apply “in a way that probably raises the actual dollar costs for most importers of such products.” 

The inclusion of copper is new since last year, says international trade lawyer, Mark Herlach, a partner at Eversheds Sutherland (US) LLP.

“Scholars of trade law had questions about the use of Section 232 for steel and aluminum, and they’re not viewed as threatening national security because we don’t need much in the way of imports for defense purposes” says Herlach. 

Copper may be another matter. President Trump has asserted that "copper is the second most widely used material by the Department of Defense," and is "indispensable" for critical U.S. infrastructure. The Department of Energy included copper on its 2023 critical materials list, and USGS added copper to its 2025 critical minerals list. In August 2025, President Trump imposed 50% tariffs on certain copper imports for the first time under Section 232. Now, he has modified them.

In any case, the president has greater freedom to impose tariffs under Section 232, because “national security is a more robust way of the president getting broad authority, so it’s a safe space if you want to exercise presidential discretion,” Herlach says. 

Explained: How Trump Can (Try to) Impose Tariffs

U.S. importers will now have to figure out which category, or annex, to the new tariff schedule applies to the products they import. “In some cases this is a simpler approach, but you’re still going to have figure out which annex you’re in,” says Herlach. “In some cases there’s a temporary transitional regime that doesn’t come into effect until the end of 2027. The takeaway is continuing complexity.”

Others point to higher costs. 

“So yes, the process has been simplified, but only through making many goods subject to heavier tariffs. It seems unlikely that many U.S. importers will consider this a win,” said Clark Packard, writing in an April 6 blog on the Cato Institute website. “Software can help with complexity, but no amount of computing power will get around this de facto tariff increase.”

Herlach points to press reports of concerns with the prior system, because the tariffs were calculated on the content, which can be hard to ascertain, and therefore more open to being manipulated by foreign producers minimizing the copper content declared.

In any case, it’s another example of the whirligig of constant change when it comes to complying with U.S. tariffs. “People are just doing the best they can, taking advantage of exemptions where they can,” says Herlach. “Nobody wants to pay more than they have to pay, so importers will  be trying to minimize their costs by finding out if they can fit within the exemptions or add more U.S. content. There’s some logic to what [the U.S. administration has] done if the goal is to have more manufacturing in the U.S., to provide an incentive for domestic production.”

Copper is used in a variety of sectors, including construction, electronics, transportation equipment, energy infrastructure and technology, and consumer products. According to estimated data from the U.S. Geological Survey (USGS), in 2025, the United States relied on imports for about 57% of total U.S. refined copper consumption. 

During expert witness testimonial April 29 before the U.S. House Natural Resources Committee’s Subcommittee on Energy and Mineral Resources, National Electrical Manufacturers Association (NEMA) President and CEO Debra Phillips noted that NEMA’s member companies have invested nearly $200 billion in domestic production capacity since 2018, and have reduced reliance on China by more than 30% during the same period. 

But she also warned how the rate and scale of U.S. grid expansion, reindustrialization, and artificial intelligence innovation and deployment depend on a secure, resilient, and affordable supply of critical minerals —  chief among them, copper. 

During the hearing, Phillips reiterated NEMA’s support for infrastructure permitting reform – including S.3947, the Reconductoring Existing Wires for Infrastructure Reliability and Expansion (REWIRE) Act, which would accelerate deployment of grid-enhancing technologies, and H.R., 4776, Standardizing Permitting and Expediting Economic Development (SPEED) Act, which would streamline federal infrastructure permit reviews and approvals.