The purpose of the study is to examine the sustainability of the tax aggressiveness of shared directors from coercive isomorphism and whether social networks of directors have an impact on their tax aggressiveness. Specifically, the study intends to examine how tax knowledge diffuses across firms and how this knowledge diffusion affects connected firms. To test the constructed hypothesis, the panel logistic regression model is estimated using a firm-level panel dataset for the US and Pakistan to analyze cross-country differences, as the USA holds more legislation and effective governance mechanisms. The study covers the period of 2007–2019. The data required for the empirical analysis was collected from the Thompson Reuters database. The results of panel logistic regression show a significant relationship between tax aggressiveness and director’s connections, suggesting that information diffuses by board interlocks. Specifically, the estimates suggest that there is a positive and significant influence of connected directors on the probability that the tax aggressiveness spreads through coercive isomorphism, inferring that the sustainability of the tax aggressiveness of shared directors from coercive isomorphism is strong. Findings reveal that Pakistani firms, when compared to the USA, are more likely involved in tax aggression because of fewer legislations and tax reforms. The results also reveal that coercive isomorphism significantly mediates the relationship between board interlocks and tax aggressiveness. These findings provide valuable insights into detecting the tax aggressiveness of firms and the channels through which this spread. The study contributes to the scarce research on the impact of board interlocks on tax aggressiveness and the influence of coercive isomorphism on these impacts. This study can help tax authorities in identifying tax-saving strategies through connected directors. Secondly, this study provides empirical evidence to support the diffusion of information regarding tax aggression and provides mechanisms with which to detect tax aggression. Third, our choice of empirical context also helps us contribute to the management practice of firms. CEOs and boards should be wary of interlocks with organizations, lest they inadvertently become reticent and hence prove to be of no good.