Laffer effect, gross substitution, marginal cost of public funds and the level property of public good provision

This paper examines the Laffer effect in the Ramsey tax-model with linear consumption taxes and a representative consumer. It is assumed that the private goods and the public good are weakly separable. It is demonstrated that if all of the private goods are weak gross complements to each other, then the Laffer effect does not exist, in other words, higher tax rates can always achieve more tax revenue. In contrast, if all of the private goods are strict gross substitutes, then the Laffer effect does exist. Moreover, if all of the private goods are weak gross substitutes, then the government cannot fully acquire the leisure endowment through taxes on consumption goods. We also show that gross substitution works to raise the marginal cost of public funds.