本文比較營利事業所得稅與個人所得稅融通生產性政府支出的總體經濟效果，我們發現當政府以營利事業所得稅作為融通工具時，最適政府規模(政府支出占GDP的比率)等於生產性政府支出的產出彈性，而且此水準的政府規模同時也能讓經濟社會的福利水準達到極大，這個發現與Barro (1990)的論點一致。但是，倘若政府以個人所得稅做為融通工具時，最適政府規模除了必須考量生產性政府支出的產出彈性外，營利事業所得稅率也會影響最適政府規模。而且，在個人所得稅融通的情境下，經濟成長極大的目標和社會福利極大的目標未必會一致，這個結論明顯不同於Barro (1990)的發現。

In this paper, we analyze the effect of business income tax financing and individual income tax financing on the productive government expenditure. We find that, under the business income tax financing scheme, the growth rate optimality condition for the productive government expenditure is the ratio of government spending to GDP equal to the production elasticity of public spending. In addition, maximizing the economic growth rate is equivalent to maximizing social welfare. On the other hand, under the individual income tax financing scheme, the optimal government expenditure not only depends on the government spending level and production elasticity of public spending, but also depends on the income tax rate. Moreover, maximizing economic growth is not equivalent to maximizing social welfare under the individual income tax financing scheme.