Caustic soda and caustic potash from China
Sodium hydroxide (caustic soda) as flakes, pearls or lye, potassium hydroxide (caustic potash) and sodium or potassium peroxides from China pay 4% UK duty, with no anti-dumping duty. They are corrosive dangerous goods, need UK REACH registration above one tonne a year, and grades for water treatment or food have their own specifications. Cambridge China Bridge sources them.
Caustic soda flakes, pearls and lye, caustic potash and sodium or potassium peroxides from China pay 4% UK duty. Purity, packing, UN numbers and an example.
4% duty
Read from the UK Trade Tariff on 26 September 2026, sodium hydroxide solid (2815 11 00 00) and in aqueous solution (2815 12 00 00), potassium hydroxide (2815 20 00 00) and peroxides of sodium or potassium (2815 30 00 00) carried 4% on goods from China, with no anti-dumping measure and no suspension. Liquid caustic soda is declared with a supplementary unit of kilograms of sodium hydroxide, so the concentration on the certificate sets the declared quantity.
Sodium carbonate is in our soda ash and carbonates guide; confirm the commodity code for the form you buy.
| Goods | Commodity code | Duty | Anti-dumping duty on China |
|---|---|---|---|
| Sodium hydroxide (caustic soda), solid | 2815 11 00 00 | 4% | None |
| Sodium hydroxide in aqueous solution (lye) | 2815 12 00 00 | 4% | None |
| Potassium hydroxide (caustic potash) | 2815 20 00 00 | 4% | None |
| Peroxides of sodium or potassium | 2815 30 00 00 | 4% | None |
Dangerous goods, REACH and grades
Caustic soda and caustic potash are corrosive, class 8 dangerous goods: solid sodium hydroxide ships as UN 1823 and solution as UN 1824, with UN-approved packaging, labels and a dangerous goods declaration for sea freight. Importing one tonne or more a year needs a UK REACH registration or an only representative, and the safety data sheet must be in English.
Sodium hydroxide for drinking water treatment is usually bought to BS EN 896, and food-grade material (E 524) must meet the specification on the [FSA register of authorised food additives](https://data.food.gov.uk/regulated-products/food_authorisations). Industrial grades are sold on assay and on impurities such as chloride, iron and carbonate.
Forms and packing
Flakes and pearls are hygroscopic and absorb carbon dioxide from air, which turns hydroxide into carbonate and cakes the product, so packing is part of the specification: 25 kg woven bags with a sealed polyethylene liner, or 1,000 kg big bags with liners, on pallets. Lye ships in IBCs or ISO tanks of stated concentration.
Worked duty example
An invented example rather than a quote: 40 tonnes of caustic soda flakes in 25 kg bags, commodity code 2815 11 00 00, bought for £16,000 free on board, with £3,000 of freight and insurance, so £19,000 is the value customs works from. Duty at the 4% rate for caustic soda is £760. VAT at 20% applies to £19,760, so £3,952. A VAT-registered buyer usually recovers the VAT, so the border adds £760 to the landed cost. See calculating UK import duty and VAT for the method.
Inspection checklist
Assay and impurities: test sodium or potassium hydroxide content by acid titration, and carbonate, chloride and iron against the certificate, on samples drawn from sealed bags of several lots.
Water and food grades: for water treatment check the material is certified to BS EN 896 with the impurity limits it sets, and for food use check the lot meets the E 524 specification, including lead and mercury.
Packing and labels: check liners are sealed and product is free-flowing, not caked, check UN 1823 or UN 1824 markings, class 8 labels and hazard pictograms on every package, and check the lot on bags matches the certificate.
What goes wrong
Caustic soda fails on packing, purity and paperwork. Torn or unlined bags let flakes absorb moisture and cake into blocks, assay comes in low with high carbonate, mercury or chlorate levels are too high for food or water use, lye arrives weaker than stated, and shipments are held for missing dangerous goods documents or an English safety data sheet.
Specify the grade and packing in the contract, test the first lot in a UK laboratory, and check dangerous goods marking and documents before loading. See our quality inspection guide.
Cambridge China Bridge sources caustic soda and caustic potash for soap and detergent makers, water treatment and chemical distributors, usually by the full container. See container programmes.
Frequently asked questions
What is the UK import duty on caustic soda from China?
Read from the UK Trade Tariff on 26 September 2026, sodium hydroxide solid and in solution carried 4% from China, with no anti-dumping duty.
Is caustic soda dangerous goods?
Yes. It is class 8 corrosive: UN 1823 for solid, UN 1824 for solution.
Why does caustic soda cake in the bag?
It absorbs moisture and carbon dioxide; insist on sealed polyethylene liners and dry storage.
Does caustic soda need REACH registration?
Imports of one tonne or more a year need UK REACH registration or an only representative.