Fiscal Externalities and Optimal Unemployment Insurance
研究发现，当失业保险只是政府总支出的一小部分时，其对所得税收入的负面影响会带来额外福利成本，即财政外部性，导致最优替代率降至零。
A common finding of the optimal unemployment insurance (UI) literature is that the optimal replacement rate is around 50 percent; however, a key assumption is that UI is the only government spending activity. I show that optimal UI levels may be dramatically reduced when UI is a small part of overall spending: the negative impact of UI on income tax revenues implies added welfare costs, a mechanism that I call a fiscal externality. Using both a standard calibrated structural job search model and a “sufficient statistics” method, I find that the optimal replacement rate is zero when fiscal externalities are incorporated.