This paper aims to extend the theoretical work of Guenther and Sansing (2010) and explain why stock ownership can proxy for the effect of investor tax status on dividend tax capitalization. We conduct a theoretical analysis that shows taxable stock ownership can represent the effect of investor tax status on tax parameter. This suggests that Guenther and Sansing's model is only applicable to tax-exempt stock ownership, but not to taxable stock ownership. In 1997, Taiwan conducted a tax reform and implemented an integrated tax system (ITS), which reduced the dividend tax rate of domestic institutional investors from 5% to 0%. By using this set of unique data, we perform empirical studies. Our finding suggests that stock ownership can proxy for the effect of investor tax status on dividend tax capitalization and is compatible with the after-tax capital asset pricing model (CAPM) and does not rely on the concept of marginal investor.