The trend is clear: states are experiencing a rapid decline in state corporate income tax revenue. Despite rebounding and even booming bottom lines for many corporations, this downward trend has become increasingly apparent in recent years. Since our last analysis of these data, in 2014, the state effective corporate tax rate paid by profitable Fortune 500 corporations has declined, dropping from 3.1 percent to 2.9 percent of their U.S. profits. A number of factors are driving this decline, including: a race to the bottom by states providing significant “incentives” for specific companies to relocate or stay put; blatant manipulation of loopholes in state tax systems by corporate accountants; significant cuts in state corporate tax rates; and the erosion of state corporate tax bases, largely due to ill-advised state-level linkages to the federal system.