Sourcing potassium dithionite from China

Potassium dithionite duty and controls

Read from the UK Trade Tariff on 29 September 2026, heading 2831 covers dithionites and sulphoxylates. Potassium dithionite falls within the other line, 2831 90 00 00, carrying 0% duty for goods from China. The supplied tariff data lists no anti-dumping or countervailing duty and no suspension.

The UK Trade Tariff attaches import and export waste controls to this line. For waste imported into England under notification controls, the exporter must apply to the competent authority in the dispatch country for consent. For dispatch from China, this means the Chinese authority. Ask your customs broker to confirm the applicable waste requirements and whether the consignment falls within their scope before shipment.

Confirm the substance and formulation using finding your commodity code. The supplied data contains only one line relevant to potassium dithionite, so the table contains that line alone. For the wider heading, see sodium dithionite sourcing.

Specify the potassium salt and active content

Name potassium dithionite explicitly in the enquiry, purchase order and batch certificate. Ask the factory to identify the substance and disclose any stabilisers or other ingredients. Agree the assay method, active content, moisture, insoluble matter, sodium contamination limits and particle form. Specify sealed packaging and agree storage instructions before approving a sample.

Establish the UK REACH registration position before ordering. Confirm with HSE whether your annual imports require registration or other coverage; registration is per substance, per legal entity. Chemicals must be correctly labelled and packaged before being placed on the Great Britain market. A safety data sheet is required when a hazardous chemical is supplied for workplace use.

Worked duty example

Illustrative example, not a quote: Illustrative order: one tonne of potassium dithionite 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: check that the purchase order, batch certificate and safety data sheet identify potassium dithionite consistently; ask a laboratory to verify identity and sodium contamination against the specification.

Assay: check a representative batch sample using the agreed method, recording active content, moisture and insoluble matter against the contractual limits.

Packaging: check seals, liners and closures for damage, leakage or moisture ingress; record caking and package condition before opening.

Traceability: match package batch marks to the analysis certificate and packing list; compare hazard information with the safety data sheet during inspection.

What goes wrong

A quotation saying only dithionite can leave the potassium salt, sodium salt or a formulated blend unclear. A certificate reporting total reducing capacity may also leave the actual potassium dithionite content uncertain. Agree identity testing and the assay basis before comparing suppliers.

Damaged closures, caking or a batch result below the agreed active content can make an otherwise matching shipment unsuitable for the buyer's process. Hold affected stock pending investigation, photograph the packaging and arrange independent analysis. Trial the approved batch in the intended process before committing to repeat orders.

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.