The EU's Carbon Border Adjustment Mechanism is penalising some of the world's most efficient producers simply because they lack access to accredited emissions verification. Default values, set at the level of the most polluting facility in a region, are applied when verified data is unavailable, creating carbon costs far above what a producer's actual emissions would justify. Upstream supply chain emissions can account for up to eighty percent of a product's footprint, compounding the problem. Reforms to expand verification access in developing markets are urgently needed.