On May 28, 2026, the Commerce Department's International Trade Administration and the Office of the United States Trade Representative jointly published a Federal Register notice that does something quietly consequential: it amends the Harmonized Tariff Schedule of the United States (HTSUS) to put the terms of a U.S.-Taiwan investment agreement directly into binding tariff law. The notice (FR document 2026-10571) is effective May 28, 2026, with the HTSUS modifications applying to goods entered for consumption on or after 12:01 a.m. Eastern on May 1, 2026 — a retroactive reach back to the start of the month that tells you the deal was settled before the paperwork caught up.
The mechanics matter, so trace them to the record. The notice descends from Executive Order 14346 of September 5, 2025, which authorized the Secretary of Commerce and the Trade Representative to implement framework trade and security agreements tied to the national emergency declared in Executive Order 14257 of April 2, 2025 — the order that established reciprocal tariffs — and to threats found under Section 232 of the Trade Expansion Act of 1962. On January 15, 2026, the American Institute in Taiwan (AIT) and the Taipei Economic and Cultural Representative Office (TECRO), the two bodies that conduct unofficial U.S.-Taiwan relations in the absence of formal diplomatic ties, signed a Memorandum of Understanding on Taiwan-U.S. Investment. On February 12, 2026, the same parties signed a broader Agreement on Reciprocal Trade (the ART). The May 28 notice implements the MOU; it explicitly does not implement the ART, because the ART had not yet entered into force.
“On September 5, 2025, President Trump issued Executive Order 14346 (Modifying the Scope of Reciprocal Tariffs and Establishing Procedures for Implementing Trade and Security Agreements).”— Federal Register source
What actually changed in the tariff schedule
The concrete tariff relief is narrow and specific. Per the notice, the MOU commits the United States to modify Section 232 tariffs applied to automobile parts, timber, lumber, and wood derivative products of Taiwan, and to remove the derivative Section 232 steel, aluminum, and copper tariffs from aircraft components that are products of Taiwan. Those are the line items written into the HTSUS annex. Notably absent from this list: semiconductors. There is no chip tariff cut in this annex, no foundry carve-out, no HBM line item. For a beat that follows the money behind chip manufacturing, that absence is the story.
The reason chips are the subtext rather than the text is structural. The United States runs no Section 232 emergency that meaningfully taxes finished Taiwanese logic chips in the way it taxes steel or autos, and Taiwan's leverage in any U.S. trade negotiation is not its auto-parts exports — it is Taiwan Semiconductor Manufacturing Company (TSMC), the indispensable foundry that fabricates the leading-edge silicon underneath nearly every American AI accelerator, smartphone, and data-center processor. When Washington and Taipei negotiate an "investment" MOU, the investment that both governments care most about is fab investment on U.S. soil. The tariff relief on lumber and aircraft components is the consideration flowing back to Taiwan in exchange for commitments that, in the broader agreement architecture, run toward onshoring advanced manufacturing capacity.
Why the split between the MOU and the ART matters
The notice is careful to implement only the MOU and to hold the Agreement on Reciprocal Trade in reserve until it "enters into force." That sequencing is a tell about how this administration is structuring industrial-policy deals. The MOU is the down payment — a set of investment commitments and limited, immediately deliverable tariff modifications that can be executed unilaterally through the HTSUS. The ART is the larger, slower instrument that presumably contains the more comprehensive tariff schedule and the binding reciprocal obligations. By splitting them, the U.S. side gets to bank Taiwan's investment commitments and deliver a goodwill tariff cut now, while keeping the bigger tariff leverage — including anything that could touch the chip supply chain — contingent on Taiwan following through.
For investors and corporate-development teams tracking semiconductor exposure, the operative read is that tariff policy and industrial policy are now the same instrument. Section 232, originally a national-security tariff authority for steel and aluminum, has become the legal scaffolding for negotiating advanced-manufacturing investment. The April 2, 2025 reciprocal-tariff emergency (EO 14257) gives the executive branch a standing lever; EO 14346 turns that lever into a deal-making mechanism that can be cashed out one trading partner at a time. Taiwan is the first major semiconductor-relevant partner to be processed through this machinery, and the May 28 notice is the first piece of binding tariff law to come out of it.
The exposure this creates
The risk this structure introduces is concentration risk dressed as relief. Because the tariff relief is delivered through a bilateral MOU rather than a most-favored-nation schedule change, it is conditional and revocable. The HTSUS annex can be amended again. Goods that benefited from the Taiwan carve-out are now exposed to the durability of a political relationship rather than to a stable tariff line. For supply chains that route Taiwanese auto parts or aircraft components into U.S. assembly — and for the much larger universe of supply chains that depend on TSMC silicon without any tariff cover at all — the lesson is that the tariff environment is now negotiated, agreement by agreement, with chips as the silent collateral.
The cleaner signal is in what was withheld. By implementing the MOU and pointedly not implementing the ART, Commerce and USTR have published, in the Federal Register, a roadmap of leverage they have chosen not yet to spend. Anyone modeling Taiwan-linked semiconductor exposure should treat the ART's eventual entry into force — and whatever chip-relevant provisions it carries — as the next catalyst to watch. The May 28 notice is not the deal. It is the first installment, and it tells you the negotiation over the chip supply chain is being conducted in the language of tariff schedules.