Poverty and income inequality have become hot topics in policy circles at the state and national levels. PPIC has been looking at these issues, too—recently analyzing the role that needs-based programs play in helping families make ends meet. In conjunction with researchers at the Stanford Center on Poverty and Inequality we measured poverty in California more comprehensively than the Census official poverty measure does. We found that the federal Earned Income Tax Credit (EITC) and refundable portion of the Child Tax Credit have the biggest impact in moderating poverty rates, relative to other safety net programs.
Both programs are aimed low- and moderate-income families with dependent children. Families must file tax returns to participate in these programs, which are funded by the federal government. (In addition, 25 states and the District of Columbia have their own smaller EITCs, although California does not.) 
The EITC is fully refundable, meaning that a family with earnings but no net tax obligation (after deductions) receives the full amount of the credit (based on their earnings) in the form of a tax refund. The Child Tax Credit is partially refundable.
Together, the EITC and CTC trimmed the 2011 poverty rate for working age adults from 24.0 percent to 21.4 percent. The child poverty rate dropped even more, from 31.1 percent to 25.1 percent. Put another way, an additional 600,000 California adults and 560,000 children would be considered poor without these programs.