This study examines the optimal tax structure in an endogenous fertility model with non-cooperative couples. In the model, both child quality and quantity are suboptimal due to the non-cooperative behavior of couples. Moreover, we consider the external effects of children on society and center-based childcare services. In such a unified model, we characterize the formulas for optimal income tax rates, child tax/subsidy rates, and tax/subsidy rates on center-based childcare services. We find that income taxation, not child subsidy, corrects the suboptimal low fertility level caused by the non-cooperative behavior of couples, and that a child tax can be optimal to alleviate the deadweight loss from income taxation. We also identify the condition under which a child subsidy is needed. The subsidy for external childcare services corrects the external effects of children on society, not the non-cooperative behavior of couples.