A 100% tariff on patented pharmaceuticals listed in the FDA Orange Book or Purple Book takes effect July 31, 2026, under a Section 232 Proclamation issued by President Trump on April 2, 2026. The action introduces a tiered rate structure with country-specific rates, multiple exemption categories, and staggered implementation dates that compliance systems must track precisely.

Tiered Rate Structure by Country of Origin

The Proclamation establishes three distinct rate tiers based on country of origin. The baseline 100% rate applies to covered pharmaceutical products from most countries, replacing existing HTSUS duty rates. Products originating from Japan, EU member states, the Republic of Korea, Switzerland, and Liechtenstein qualify for a reduced 15% rate. UK-origin products face the steepest burden: 100% plus an additional 10% surcharge, totaling 110%, though this rate is reducible to zero contingent on a future bilateral pharmaceutical pricing agreement.

Rate Summary: 100% (general) | 15% (Japan, EU, Korea, Switzerland, Liechtenstein) | 110% (UK, reducible via bilateral agreement)

Exemption Categories for Classification Systems

Generic pharmaceuticals, biosimilars, and their associated APIs are expressly excluded from Section 232 coverage. U.S.-origin pharmaceutical products, APIs, and key starting materials are also exempt. Drugs designated as orphan under the Orphan Drug Act (21 U.S.C. § 360aa et seq.) qualify for exemption across all approved indications. Annex IV of the Proclamation lists specific 10-digit HTSUS codes that receive zero-rate treatment—compliance engineering teams must parse this annex to flag exempt classifications in their systems.

Additional specialty categories exempt from the tariff framework include nuclear medicines, plasma-derived therapies, fertility treatments, cell and gene therapies, antibody drug conjugates, CBRN medical countermeasures, and animal health products. Goods classifiable under HTSUS 9817.85.01 as prototypes for development, testing, or quality control purposes may also qualify for exclusion.

Dual Implementation Dates

Critical for rate caching: Two effective dates apply. July 31, 2026 is the general implementation date. Companies listed in Annex III receive delayed implementation until September 29, 2026—a 60-day gap that requires date-sensitive rate logic.

The 17 companies identified in Annex III are not subject to the 100% duty until the later September 29, 2026 date. Companies listed in Annex II that entered into MFN pricing agreements with HHS prior to April 2, 2026 are fully exempt. Firms with Commerce-approved onshoring plans face a +20% surcharge on top of applicable rates until April 2, 2030, unless they also execute an HHS MFN agreement, which provides tariff relief through January 20, 2029.

HTSUS Modifications and Classification Impact

Annex I of the Proclamation modifies the Harmonized Tariff Schedule of the United States, establishing a tiered framework of mutually exclusive headings for calculating duties on pharmaceutical products, APIs, and key raw materials. Classification systems must differentiate between Annex I provisions (subject to tariff) and Annex IV codes (exempt). The covered scope includes active pharmaceutical ingredients and key starting materials for Orange Book and Purple Book products—not just finished dosage forms.

Trade compliance engineering teams should validate classification logic against both annexes, implement country-of-origin rate lookups supporting all three tiers, and configure date-aware rate application to handle the July 31 versus September 29 split. Rate caching must account for the UK's conditional rate reduction tied to future bilateral agreements.

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