HS Code 26.21 – Slag and ash n.e.c. in chapter 26; including seaweed ash (kelp) and ash and residues from the incineration of municipal waste

HS code 2621 is a 4-digit heading in the Harmonized System that covers: Slag and ash n.e.c. in chapter 26; including seaweed ash (kelp) and ash and residues from the incineration of municipal waste. Heading 2621 is a crucial "n.e.c." (not elsewhere specified) category within Chapter 26, encompassing "Slag and ash n.e.c. in chapter 26; including seaweed ash (kelp) and ash and residues from the incineration of municipal waste." This heading serves as a catch-all for various slags and ashes that do not fit into the more specific categories of 2618 (granulated iron/steel slag), 2619 (other iron/steel slag), or 2620 (metal/arsenic-containing slag/ash not from iron/steel). The scope is broad, covering a diverse range of residues from combustion or industrial processes, provided they are not specifically covered elsewhere in Chapter 26 and do not contain significant levels of metals or arsenic as defined by 2620. Key sub-categories include municipal solid waste incineration ash (bottom ash, fly ash), seaweed ash (kelp), and various other non-hazardous industrial or agricultural ashes. This classification is vital for trade compliance as it helps to correctly categorize residues that might otherwise be difficult to place, ensuring proper handling, disposal, or valorization. Historically, many of these materials were simply landfilled, but increasing environmental regulations and resource recovery initiatives have led to their use in construction, agriculture, or as raw materials. As part of Chapter 26, it reinforces the systematic classification of mineral products and their by-products, ensuring that all forms of slag and ash are accounted for within the HS nomenclature.

Incinerated municipal solid waste ash, bottom ash from waste-to-energy plants, fly ash from waste-to-energy plants, seaweed ash (kelp ash), wood ash (if not specifically classified elsewhere), straw ash, rice husk ash, sewage sludge ash, boiler ash (non-metal rich, non-coal), agricultural waste ash, plant residues ash, activated carbon spent ash (not metal-rich), spent foundry sand (non-metal rich), power plant ash (non-coal, non-metal rich), biochar ash, volcanic ash (if industrial waste by-product), non-hazardous industrial waste ash, paper mill sludge ash, ceramic waste ash, glass polishing residues (ash form), carbon black waste ash, gypsum waste ash.

A common misclassification for HS 2621 is confusing it with HS 2620 (slag, ash, and residues containing metals or arsenic). The crucial distinction is the absence of significant metal or arsenic content in 2621; if these elements are present, it falls under 2620. Another error is classifying highly specialized industrial wastes, particularly those with hazardous properties not related to metal/arsenic content, under 2621. Such materials might belong to Chapter 38 (e.g., HS 3825 for municipal waste or chemical residues) if they are considered hazardous or specifically defined. The 'n.e.c.' nature means it's a residual category, so specific classifications always take precedence.

In 2025, the top exporters of HS code 2621 in UN Comtrade data were India ($78M, 19% of world exports), China ($51M) and the Netherlands ($41M). World exports came to about $411M, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.

In 2025, the top importers of HS code 2621 in UN Comtrade data were the Netherlands ($57M, 12% of world imports), Bangladesh (about $52M) and Germany ($40M). World imports came to about $495M, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.

HS code 2621 is a 4-digit heading under Chapter 26 of the Harmonized System. The first 2 digits (26) identify the chapter, and digits 3-4 (21) specify the heading. This code contains multiple 6-digit subheadings for precise product classification.