In this brief, we consider both personal and business income tax expenditures at the state level. We use California, Massachusetts, Minnesota, and the District of Columbia as examples. We separate tax expenditures into those that occur because of conformity with federal tax provisions and those that result from state-specific tax policies. We find that the former category accounts for between 70 and 85 percent of the total cost of combined individual and business income tax expenditures. We also find that except for certain economic development and income security provisions common to many states, state-specific tax expenditures vary considerably by state.