Objective: The aim of the present study is to investigate the effect of social responsibility on the lack of transparency of operating cash flow with an emphasis on the role of tax avoidance.

Research method: The present study is applied and from the methodological perspective, the correlation is of a causal (post-event) type. The statistical population of the study was all companies listed on the Tehran Stock Exchange, and using the systematic exclusion sampling method, 141 companies were selected as the research sample and were examined over a 10-year period between 2014 and 2019.

Findings: The results of testing the research hypotheses showed that social responsibility has a negative and significant effect on the lack of transparency of operating cash. Tax avoidance also affects this relationship. Tax avoidance has a moderating and weakening role.

Conclusion: The results of this study showed that corporate social responsibility can significantly reduce operating cash opacity and play an important role in improving financial transparency. However, the findings indicate that tax avoidance as an intervening factor can affect this relationship and, in interaction with social responsibility, increase the level of operating cash opacity. This indicates that simply paying attention to social responsibility without controlling tax behaviors may not fully improve financial transparency. From a knowledge-building perspective, this study provides a more detailed understanding of the factors affecting the transparency of corporate cash flows by combining the two important variables of social responsibility and tax avoidance.