Sourcing sulphonamides from China
Sulphonamides from China have a 6% UK duty rate with no anti-dumping, but 23 of 43 lines are suspended to 0% until 2028, including toluenesulphonamides, OBSH and sulfonylurea herbicides such as nicosulfuron and tribenuron-methyl, and the residual line is 0% for listed pharmaceutical substances. PFOS sulphonamides are banned as persistent organic pollutants.
Sulphonamide APIs, sulfonylurea herbicides, toluenesulphonamides and OBSH from China: 6% UK duty, many 0% suspensions, 0% for listed pharmaceuticals.
6% duty, suspensions and pharmaceutical relief
Read from the UK Trade Tariff on 27 September 2026, heading 2935 covers sulphonamides. Of its 43 lines, one named compound carried 0% and the rest 6% on goods from China, with no anti-dumping measure. Twenty-three lines have a full 0% suspension to 31 December 2028, including toluenesulphonamides, 4,4'-oxydi(benzenesulphonohydrazide) (OBSH, a blowing agent), florasulam, penoxsulam, rimsulfuron, thifensulfuron-methyl, nicosulfuron, tribenuron-methyl, flazasulfuron, propoxycarbazone-sodium, venetoclax and several pharmaceutical intermediates. Listed lines without a suspension, such as encorafenib, vemurafenib and lenacapavir sodium, pay 6%.
The residual line (2935 90 90 99), where many generic sulphonamide drugs fall, shows two rates: 0% under additional code 2500 for pharmaceutical substances listed in Tables 10 to 13 of the customs reliefs reference document, and 6% under code 2501 for everything else, with a suspension for named substances such as bensulfuron-methyl. Confirm the commodity code and whether the substance is on the pharmaceutical list.
| Goods | Commodity code | Duty | Anti-dumping duty on China |
|---|---|---|---|
| PFOS sulphonamides (banned as POPs) | 2935 10 00 00 | 6% | None |
| Toluenesulphonamides | 2935 90 90 20 | 6% (0% suspension to 31 Dec 2028) | None |
| Penoxsulam | 2935 90 90 42 | 6% (0% suspension to 31 Dec 2028) | None |
| Nicosulfuron, 91% or more | 2935 90 90 63 | 6% (0% suspension to 31 Dec 2028) | None |
| 4,4'-Oxydi(benzenesulphonohydrazide) (OBSH) | 2935 90 90 50 | 6% (0% suspension to 31 Dec 2028) | None |
| Vemurafenib, 98% or more | 2935 90 90 29 | 6% | None |
| Other sulphonamides | 2935 90 90 99 | 0% listed pharmaceuticals; 6% other | None |
POPs, pesticides, medicines and REACH
Perfluorooctane sulfonic acid and its derivatives, including its amides, are listed in Annex I of retained Regulation (EU) 2019/1021 on persistent organic pollutants, so PFOS sulphonamides cannot be placed on the market. Sulfonylurea herbicides and other plant protection actives can only be used in products authorised in Great Britain under retained Regulation (EC) No 1107/2009.
Active substances for human medicines are regulated under the Human Medicines Regulations 2012: importers must be registered with the MHRA and the substance must be made to good manufacturing practice. Other uses need UK REACH registration above one tonne a year under retained Regulation (EC) No 1907/2006.
Specifying sulphonamides
Specify the CAS number, grade (pharmaceutical, technical or agrochemical), assay by HPLC, related substances and residual solvents, particle size, water content, packing, retest date and certificate of analysis, and for APIs the GMP documentation and pharmacopoeial monograph.
Worked duty example
Take a hypothetical order of 5 tonnes of penoxsulam technical, entered under 2935 90 90 42: £150,000 free on board plus £3,000 of freight and insurance gives a customs value of £153,000. Penoxsulam carry no duty, so import VAT of 20% on £153,000, £30,600, is the only tax. A VAT-registered importer normally reclaims it, so the border adds no lasting cost. That assumes the suspension is claimed; without it the 6% rate would add £9,180. Step by step: UK import duty and VAT.
Inspection checklist
Documents: check the certificate of analysis, the suspension or pharmaceutical-list basis for any 0% claim, GMP evidence for APIs and the REACH route for other uses.
Laboratory: test assay, impurities and residual solvents on an independent sample against the specification or monograph.
Packing: check drums or bags are sealed, labelled with batch numbers and GB CLP pictograms, and protected from moisture.
What goes wrong
Sulphonamide orders fail on paperwork, impurities and classification. APIs arrive without the GMP evidence buyers need, impurity profiles differ from the reference, a 0% rate is claimed for a substance that is not on the list, and banned PFOS derivatives appear in technical mixtures.
Settle the regulatory route first, test independently, and check the tariff basis for each substance. See our quality inspection guide.
Cambridge China Bridge sources sulphonamide intermediates and agrochemical actives for UK manufacturers, checking the producer's GMP and quality records first. See factory verification.
Frequently asked questions
What is the UK import duty on sulphonamides from China?
Read from the UK Trade Tariff on 27 September 2026, 6% on most lines, with 23 suspended to 0% until 2028.
Are sulphonamide drugs duty-free?
On the residual line, listed pharmaceutical substances are 0% under additional code 2500; others pay 6%.
Can PFOS sulphonamides be imported?
No. PFOS and its derivatives are listed in the persistent organic pollutants regulation.
Do API importers need to register?
Yes. Importers of active substances for human medicines must be registered with the MHRA.