In April, Washington put a 100% tariff on imported patented medicines, and the number did all the talking. The line that matters more to American research labs arrived six months later, buried in a customs notice: a zero-duty heading for material imported solely for research. Customs does not take the word “research” on faith, though. It takes records.
What the April proclamation actually taxed
Proclamation 11020, signed on April 2, 2026 under Section 232 of the Trade Expansion Act of 1962, closed a Commerce Department national security investigation that opened in April 2025. It set a default 100% duty on patented pharmaceutical products and their associated ingredients. That definition reaches past finished medicines to active pharmaceutical ingredients (APIs) and the key starting materials used to make them.
Coverage is set by a list of tariff codes in Annex I of the proclamation. A product description or a line on a label decides nothing on its own.
The 100% figure was always a ceiling more than a typical bill. Generic drugs and biosimilars, along with their ingredients, were left out. Goods from the European Union, Japan, South Korea and Switzerland face 15%. A company with an approved plan to move production onto US soil pays 20%, a discount scheduled to climb back to 100% on April 2, 2030. Products of US origin are not subject to the tariff at all.
The duties arrived in two waves. Under U.S. Customs and Border Protection’s implementation guidance (CSMS #69395344), the 17 companies named in Annex III began paying on July 31, 2026. Everyone else followed on September 29.
The September change most people missed
On September 23, the Commerce Department published guidance and technical corrections in the Federal Register (91 FR 60360). Six days later, CBP turned them into updated filing instructions, CSMS #70054007. Most coverage filed it under housekeeping. It deserved a closer read.
The update created a new tariff heading, 9903.04.70, with a 0% additional duty for pharmaceutical articles and ingredients imported solely for clinical trials, research and development, or other non-commercial use. A neighboring heading, 9903.04.69, adds no Section 232 duty for goods classified in covered chapters that fall outside the proclamation’s patented and generic definitions. Which heading a given research compound belongs under is exactly the kind of call an importer should not make alone. The same guidance cut the UK rate from 10% to zero, and CBP confirmed that when more than one rate could apply, the importer pays the lowest.
For anyone importing research material, that looks like a gift. Read the word “solely” twice before opening it.
“Research use” is a claim, and customs wants the evidence
Trade lawyers have been direct about what the research heading demands. A WilmerHale client alert dated October 15, 2026 told importers to document intended use before goods are entered and to keep controls that stop research material from being diverted into commercial sale. The exemption follows what actually happens to the material and the records that prove it. The wording on the vial carries no weight.
Anyone who has spent time around research peptides will recognize the problem. “For research use only” appears on nearly every label in the trade, and as a legal matter it has never proved much by itself. The new heading simply adds a customs officer to the list of people entitled to ask what the material is really for.
There is also a gray zone the public summaries leave open. None of them explain how CBP will treat a distributor that imports material in order to resell it to university and contract labs. Is that research use, or commercial sale with a research customer at the end of it? An importer in that position should get specific customs advice before it risks a shipment on the answer.
Customs decides origin by where the molecule was made
The US-origin exemption raises a question that sounds simple and isn’t: where was this peptide made? A shipping label doesn’t settle it. In customs law, a good generally takes the origin of the last country where it underwent a substantial transformation, meaning it became a new article with a different name, character or use. Splitting a bulk powder into smaller vials and printing a domestic address on the carton does not normally clear that bar.
The proclamation’s own structure points the same way. CBP’s July guidance gives a 0% rate to certain finished dosage forms made with US-origin APIs, which says plainly that the government locates the value in the active ingredient.
Peptides make the origin question harder than most chemicals do. A sequence is assembled one amino acid at a time on a solid resin support, the method that earned Bruce Merrifield the 1984 Nobel Prize in Chemistry. Making the protected amino acids, building the chain, cleaving it from the resin, purifying it and freeze-drying the result can happen in separate facilities, sometimes on separate continents. Whether a protected building block or a crude peptide lands in an Annex I code is a technical classification call. The importer of record has to make it, and the scientist who eventually opens the vial never sees that decision.
The part of the chain a lab buyer can control is the end of it. A supplier that keeps inventory on domestic shelves takes the border out of each delivery. USA Peptide Depot, for example, says every order is stocked and dispatched from inside the United States with tracking, so the customs step happens once, upstream, instead of on every parcel headed to the bench. Domestic stock answers the delivery question. The origin question still belongs in the supplier’s paperwork, and that is where a buyer’s leverage now sits.
Four questions worth putting to any peptide supplier now
None of this requires a lab manager to become a customs broker. It does make a few ordinary supplier questions more useful than they were a year ago.
- Where was this material synthesized, and will you state that in writing for the lot I am buying?
- Is the sequence a patented drug substance, an off-patent compound or a research material that sits outside the pharmaceutical definitions? The answer shapes what the supplier pays at the border, and what it may pass on to you.
- Does the lot number on my vial match a specific analytical report I can open, or is one certificate being reused across batches?
- Is the stock already in the country, or will my order cross a border after I pay for it?
The third question is the one a serious supplier can answer today without a phone call. Some publish the report against each lot so the buyer never has to ask. usapeptidedepot.com matches each lot to the chromatography report filed against it, posts independent HPLC results where testing is available, and lays out its testing approach on its standards page. That habit matters beyond purity. A business that already ties every vial to a document is set up to answer an origin or end-use question quickly, and speed counts for more when a customs officer may be the one asking.
What to watch before spring
The generic exemption is provisional. The proclamation gives Commerce one year, until early April 2027, to tell the President whether generic drugs and their ingredients should be pulled in. By the FDA’s count, generics fill about nine in ten US prescriptions, so that decision would reach far deeper into the supply chain than the patented tier does.
The onshoring discount has an expiry date too. Companies paying 20% under approved plans are scheduled to face the full rate from April 2030, which gives them a fixed deadline to have domestic production running.
In April, the White House also said Section 232 reviews were underway in neighboring sectors, including personal protective equipment, medical consumables and medical equipment. Labs buy plenty of all three.
Then there is the research heading itself, which is only weeks old. How strictly CBP reads “solely” will become clear through rulings, audits and the first rejected entries, and press releases will not settle it.
For a lab manager, the useful step costs nothing: ask suppliers for origin and lot documentation now, while it is still a routine request. A supplier that cannot produce those papers in November will not find them any easier when the person asking works for CBP.
