本文研究企業社會責任表現與租稅規避行為是否有互為因果之關係，以及產品市場競爭對此關係的干擾效果。樣本為2010年到2019年獲得天下雜誌企業公民獎的臺灣上市上櫃公司，以及利用傾向分數配對的未得獎公司作為控制組。本文以道德倫理假說解釋社會責任表現與避稅程度互相負向的影響；以成本補償假說和形象彌補假說解釋互相正向的影響。分別以企業公民獎評分和財稅差異衡量社會責任表現和避稅程度，迴歸結果發現：企業社會責任表現與公司避稅程度互為因果；公司的社會責任表現正向影響避稅程度，成本補償假說成立；避稅程度正向影響社會責任表現，支持形象彌補假說；產品市場競爭減弱成本補償現象、增強形象彌補行為。另進行穩健性檢查，包括以前期避稅行為解釋次期企業社會責任、以得獎與否的指標變數衡量社會責任表現，及以剩餘財稅差異衡量避稅程度，結論仍不變。

This research explores whether there is a causal relationship between corporate social responsibility (CSR) performance and tax avoidance behavior and examines the interference effect of product market competition on such correlation. The sample consists of TWSE and OTC companies that won the Corporate Citizenship Award of Commonwealth Magazine from 2010 to 2019 as well as non-winning companies obtained by the propensity score matching. We use the moral and ethical hypothesis to explain the mutual negative influence between CSR performance and the degree of tax avoidance along with the cost compensation as well as the image compensation hypotheses to explain their mutual positive effect. CSR performance and tax avoidance are measured by the corporate citizenship award score and book-tax differences, respectively. The empirical results show the following. 1) CSR and tax avoidance exhibit causality to each other. 2) CSR performance positively affects its tax avoidance, and thus the cost compensation hypothesis holds. 3) The degree of tax avoidance positively affects CSR performance, supporting the image compensation hypothesis. 4) Product market competition reduces the phenomenon of cost compensation and enhances the behavior of image compensation. Some robustness checks are executed, including the next-period CSR explained by the previous tax avoidance behaviors, the CSR performance as measured by the indicator variable for whether awards are granted or not, and the degree of tax avoidance as measured by residual book-tax differences. The conclusions remain unchanged.