HS 2815.11: how caustic soda is classified, and what it decides

Most caustic soda enquiries open with the same number: HS 2815.11. It is the right starting point — and on its own it decides very little about what you pay. What decides that is the physical form of the material, the country of origin rather than the country it ships from, and whether a trade measure is in force. All three have to be checked rather than assumed.

Heading

2815 · Chapter 28

Solid form

2815.11

Liquid form

2815.12

What we ship

Flakes, 99% min

Transport class

UN 1823 · Class 8 · PG II

Origin

China — our own plant, Wuhai

What HS 2815.11 covers, and what it does not

Heading 2815 sits in Chapter 28, the chapter for inorganic chemicals. The heading itself covers sodium hydroxide (caustic soda), potassium hydroxide (caustic potash) and the peroxides of sodium and potassium. The subheading then splits sodium hydroxide by physical state: 2815.11 for the solid form and 2815.12 for sodium hydroxide in aqueous solution, the form the trade calls liquid caustic or soda lye.

“Solid” is broader than flakes. Pearls, granules, blocks and any other dry, anhydrous form of the same chemical sit in 2815.11 as well. The subheading follows the chemistry, not the commercial description, which is why purity, bag size, palletisation and private label do not move a shipment from one line to another. What does move it is the product no longer being sodium hydroxide on its own: a blend or preparation with other functional ingredients can fall under 3824 as a chemical preparation, or under 3402 where it is formulated as a cleaning product. Potassium hydroxide is a different subheading again, 2815.20, and the two are confused often enough that it is worth naming the chemical on the invoice.

The first six digits are the same in every country that uses the Harmonized System. Beyond six digits each country adds its own national lines and its own legal notes, so your tariff number and ours agree up to the sixth digit and can part company after it. That is normal, and it is why the level two parties can agree in a contract is the six-digit subheading.

Why the solid/liquid split is the expensive mistake

Declaring a solution on a solid line, or the other way round, is the most common classification error in this product — and it is not cosmetic. The two subheadings carry different duty treatment in some markets, different import authorisations, and different transport rules: solid caustic soda travels as UN 1823, the liquid form as UN 1824, in a tank or IBC rather than in bags. The cost of getting it wrong lands on the importer of record: reassessed duty, penalties, a container held at the port while the declaration is corrected, and a classification history a customs authority can review again on every later entry.

It is a commercial question before it is a customs one, too. What you are buying is NaOH, not water: a loaded container of flakes carries roughly 25 tonnes of the chemical, while liquid caustic delivers about half its weight as NaOH once the water is counted. Comparing the two on cost per tonne of product rather than per tonne of NaOH is the fastest way to make an expensive mistake, and the arithmetic is set out in flakes vs pearls vs liquid.

What the classification triggers before the container moves

Get the code right and a predictable set of requirements follows from it. These are the documents and permissions a caustic soda entry generates:

• Hazard communication — an SDS written to the GHS model, and packaging labelled to match it, in the language your authority requires. Ours travels with every shipment and is listed with the rest of the set on documents and downloads.
• Dangerous goods handling — UN 1823, Class 8, packing group II for the solid form: a dangerous goods declaration, Class 8 markings, and the packaging documentation your carrier requires. A DG booking takes longer and costs more to handle than a dry box, which is why our lead times assume it — see packing and container loading.
• Batch quality evidence — a certificate of analysis for the lot you receive, on the same specification the offer quotes. Ours is on the caustic soda flakes page.
• Import-side authorisations, which belong to you as importer of record rather than to us: hazardous or toxic materials registration in Indonesia, the chemical import declaration in Vietnam under the 2026 Chemicals Law, conformity certification at origin for Nigeria's SONCAP programme, the PVoC schemes in East Africa. Our Indonesia and Vietnam pages set out the clearance sequence for those two markets, and more are listed under supply by market.
• The duty and tax base — in most markets duty is charged on the CIF value and VAT on the CIF value plus duty. Since a CIF price stops at the port, the number on your cost sheet and the number in the contract are not the same figure; what belongs in a comparison is landed cost, which is the subject of what drives the price.

Preferential duty: what a certificate of origin actually does

Because the material is China-origin, the certificate that changes your rate is the one that matches your market's agreement with China. For ASEAN destinations that is Form E under the ASEAN–China Free Trade Area; several markets in the region are also party to RCEP, so your broker may have two preferential routes to compare and should claim the better one. Form D is a different certificate and applies to material originating inside ASEAN, so it is not the right instrument for China-origin goods.

A certificate of origin is an origin claim, not a discount coupon. It lets your broker claim the preferential rate where the rules of origin are met, and it has to tell the same story as the invoice and the packing list: one origin, stated consistently, on every document. What it does not do is remove VAT, cancel a trade measure, or repair a wrong classification — an anti-dumping duty follows the origin of the goods whatever rate you qualify for under an FTA. We issue the certificate that fits your market with the shipping documents, and we state the origin in the offer. The clearance sequence for our two largest markets is set out on the Vietnam and Indonesia pages.

Anti-dumping and countervailing duty: check the scope, not the code

This is the part of the cost a supplier's quotation rarely addresses, so it is worth understanding how customs authorities actually apply it. An anti-dumping or countervailing duty is not a tariff line: it is an order issued after an investigation, with a written description of the product, the countries and the parties it covers — the scope. Customs authorities are explicit that the tariff codes listed in an order are provided for convenience, and that the written description of the scope governs. Two consequences follow that surprise buyers:

• Material can be in scope even when it enters under a different code — and out of scope even when it enters under a code the order lists. The code is a hint; the scope text is the rule.
• Origin, not the port of shipment, decides. China-origin goods routed through a third country do not become third-country goods unless a substantial transformation happened there, and an intermediating trader changes nothing. Investigators have also extended measures to specifically named third-country processing routes.

The rate then depends on who produced and who exported it. Most systems work down a cascade: a rate for a named producer–exporter combination, then a rate for the exporter, then the producer, and failing all of those an “all others” or country-wide rate — which in non-market-economy cases can be a multiple of the company-specific figure. Which is why the invoice, the packing list and the entry summary have to name the producing plant. “Sold by a trader, made by an unnamed factory” is the shortest route to the highest rate available.

One more thing worth planning for: the duty deposited at entry is provisional. The final assessment is normally settled months later through an administrative review, and the assessed rate can come back higher or lower than what was paid at the border. On a container-sized first order that is a working-capital question, not a rounding error.

How to check your own exposure in five steps

None of the sources below is a supplier's website, including this one. A rate that matters should come from the authority that will apply it to your entry:

• 1. Classify in the form you actually buy. Solid or liquid first, then your national line; six digits is the level two parties can agree in a contract.
• 2. Read your own tariff. The national schedule or customs-union tariff is the only authoritative source for a duty rate — for example the US Harmonized Tariff Schedule or the EU's Access2Markets service, which also carries the measures in force.
• 3. Search for a measure in force. Check several digit levels, because a scope paragraph citing a six-digit subheading sweeps in every national line beneath it. Official starting points: the US CBP anti-dumping and countervailing duty pages, and India's Directorate General of Trade Remedies.
• 4. Confirm origin and name the parties. Country of origin on every document, plus the manufacturer and the exporter by name, so the correct rate tier can be matched at entry.
• 5. Confirm what the importer of record must hold before the vessel sails: licence, hazardous-materials registration, conformity certificate, product registration. This is the step that most often delays a first shipment, and it is quicker to fix before loading than after arrival.

The nomenclature itself is defined by the World Customs Organization, and the section covering Chapter 28 is worth reading once — it is shorter than most summaries of it.

Where the measures sit at the moment

Trade measures move faster than tariffs do. Read the notes below as the state of play when this page was written, not as a permanent map, and verify with the sources above before you contract.

Published Chinese customs statistics for 2026 put solid sodium hydroxide exports highest to Indonesia, Vietnam and Ghana — the destinations we concentrate on — and the trade has grown through the year. Wherever your market sits, the practical rule is the same: ask your customs broker what applies to HS 2815.11 from China, and ask us, in writing, for the origin and the producing party that will appear on your documents.

Why the producer's name on the paperwork matters

We are the plant, not a middleman trading a container it never sees. The commercial invoice, the certificate of analysis and the export documents carry the name of the producing company, Inner Mongolia Tianshun Alkali Industry Co., Ltd., because that is the entity that makes the flakes and files the export declaration. In a market where a trade measure applies that is not a small detail: it is what lets your broker match your entry to a producer-specific rate instead of falling back on the rate for unnamed parties. It also means your technical questions reach the people who run the evaporation unit rather than someone reading a specification sheet. What our documents prove, and how to check them, is covered in how to check a Chinese supplier.

Questions buyers ask about HS codes and duty

Related: what drives the price of caustic soda flakes · how to check a Chinese supplier before you pay · documents and downloads · receiving and checking a shipment.