HTS code 2621.10.00.00 covers "Other slag and ash, including seaweed ash (kelp); ash and residues from the incineration of municipal waste › Ash and residues from the incineration of municipal waste" under the US Harmonized Tariff Schedule. This is the official duty rate charged by US Customs when this product is imported into the United States, sourced directly from the U.S. International Trade Commission and refreshed daily.