This study examines how cost uniqueness, defined as the distinctiveness of firms’ cost patterns relative to peers, affects strategic outcomes by altering information environments. Cost uniqueness reflects firm-specific patterns of resource acquisition, allocation, and utilization that are inherently opaque and difficult for outsiders to benchmark. Using corporate tax avoidance as the empirical setting, we argue that this opacity lowers detection risk by tax authorities and enables firms to adopt more aggressive tax strategies. Using a large sample of US firms from 1994 to 2022, we find that cost uniqueness is positively associated with tax avoidance. This association is weaker when transparency is greater through higher institutional ownership, more analyst coverage, and greater financial statement comparability. Importantly, we do not find evidence that cost uniqueness attracts greater IRS scrutiny or enforcement. Overall, our study highlights how operational distinctiveness affects corporate decision-making, specifically tax behavior.