Behavioral Responses to State Income Taxation of High Earners: Evidence from California

Using administrative income tax data, we analyze the response to Proposition 30, a 2012 ballot measure that increased California marginal tax rates by up to 3 percentage points for high-income households.Relative to baseline rates of departure for their income levels, an additional 0.8% of the residential tax base that landed in the top bracket left California in 2013.Using matched outof-state taxpayers as controls reveals an income elasticity with respect to the marginal net-of-tax rate of 2.5-3.2 for high-earners who stayed.These responses together eroded 45.2% of state windfall tax revenues within the first year and 60.9% within two years, with the extensive margin accounting for 9.5% of this total.