Sourcing calcium sulphoxylate from China

Duty and waste controls

Read from the UK Trade Tariff on 29 September 2026, heading 2831 covers dithionites and sulphoxylates. Calcium formaldehyde sulphoxylate falls within the other line, 2831 90 00 00. Goods from China carry 0% duty, with no anti-dumping or countervailing measure and no suspension recorded.

The tariff attaches waste import and export controls. For waste imported into England under notification controls, the exporter must apply to the dispatch country's competent authority for consent. Before ordering material described as waste from China, confirm the applicable import requirements with your customs broker. Confirm export controls separately before returning waste to China.

Confirm the chemical identity, composition and commodity code before shipment, particularly for formulated products. For wider heading coverage, see the sodium formaldehyde sulphoxylate guide.

Specify the calcium compound and assay

Write calcium formaldehyde sulphoxylate into the purchase specification rather than accepting a trade name alone. Agree chemical identity, physical form, active content, moisture, insoluble matter and particle size. Ask the factory to explain whether its assay is reported on the supplied material or a dry basis, and specify the test method.

Request a batch certificate of analysis and an approved sample for a trial in your process. Agree dissolution conditions, acceptable residue and reducing performance against that sample. Specify sealed packaging, batch identification and storage instructions consistent with the supplier's safety data sheet.

Confirm with HSE whether UK REACH registration is required for the exact substance and your importing business. Registration is per substance and legal entity. Chemicals must be correctly labelled and packaged before sale in Great Britain. A safety data sheet is required when a hazardous chemical is supplied for use at work.

Worked duty example

Illustrative example, not a quote: Illustrative order: one tonne of calcium formaldehyde sulphoxylate under 2831 90 00 00, invoiced at £15,000 free on board, with £2,000 of freight and insurance to the UK. The customs value is £17,000. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £17,000, so it is £3,400. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Inspection checklist

Identity: match the calcium compound on the order, safety data sheet, certificate and container labels; investigate any sodium compound description.

Assay: independently test a representative batch sample using the agreed method; compare active content, moisture and insolubles with the contract.

Process trial: compare dissolution, residue and reducing performance with the approved sample under your agreed operating conditions.

Packing: check seals, liners, net weight, batch marks and signs of moisture or caking; compare hazard labels with the safety data sheet during inspection.

What goes wrong

A trade name can conceal a different compound or a formulation. An assay reported on a dry basis can also look acceptable while the supplied material contains more moisture than agreed. Treat unclear identity, missing test methods and certificates without matching batch references as reasons to hold the shipment for clarification.

Caking, damaged liners, excess insoluble residue and inconsistent process performance are useful rejection checks. Agree the sampling method and acceptance criteria before ordering, and keep an approved sample for comparison when the shipment arrives.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For repeat volumes, see container programmes.