The Louisiana Board of Tax Appeals corrected the Louisiana Department of Revenue’s incorrect denial of a taxpayer’s refund claim for the purchase of sodium hydroxide. The sodium hydroxide was used by the taxpayer to reduce the toxicity of their manufacturing waste to be in compliance with state and federal pollution control laws. After being denied a sales tax refund for the materials, the taxpayer petitioned to appeal the refund denial in the amount of $3,960,969.48 in sales tax paid on purchases of sodium hydroxide, or caustic, between the dates of January 1, 2012 to December 31, 2014. The board explained that the caustic materials were a pollution control device or system (PCDS) that should be eligible for the state sales tax exclusion. (Louisiana Board of Tax Appeals, Docket No. 11389D, April 14, 2021)