In this mixed methods dissertation, I examine how definitions of family shape decisions to apply for the Earned Income Tax Credit (EITC), which family members to include as dependents on the EITC application, and to whom in one’s family benefits are shared. EITC policy largely ignores family structures that include multi-generations, adult siblings, and adult children that may or may not live under one roof. This creates a misfit between EITC eligibility and the realities of family life for many, particularly for families of color due to historical and contemporary punitive and exclusionary policies, and socio-cultural and economic factors that shape family life. The study is informed by secondary analyses of survey data and in-depth interviews with thirty single women with children – primarily women of color - who receive the EITC. I use the Survey of Income and Program Participation (SIPP) to estimate household living arrangements of EITC-eligible families. For the interviews, I recruited a sample of women in diverse living arrangements. Using the SIPP, I establish the centrality of extended family systems in EITC-eligible households. About forty percent of EITC-eligible single women with children share household living arrangements with at least one other adult. Most of these women are the financial head of household, with women of color disproportionately comprising these household types. Extended household living arrangements appear to provide differential economic support by race/ethnicity. My analyses suggest the current EITC structure is insufficient for addressing the economic and income poverty issues that single women encounter. Interview data revealed the importance of extended family in EITC allocation decisions. My analysis shows that many interviewees allocate a portion of their EITC to their adult children, mothers, and family caregivers – despite receiving no tax credit for doing so. For example, some respondents report giving lump sum payments to family members, typically their mothers, who provided regular childcare during the year. Respondents highlighted the social and economic value of the childcare in helping them participate in paid work, attend school, and have a balanced life. These dynamics were most prominent among the Black women interviewed, some of whom described a sense of indebtedness to their mothers that motivated them to give a portion of their EITC consistently for many years after their children were grown. I also provide evidence that the filing of taxes and allocation of the EITC is a site of negotiation and intergenerational support between parents and young adult children. Respondents described a negotiated and relational process with their young adult children around tax filing and how they viewed tax filing as a symbolic "mini-transition" within their child's broader transition to adulthood. My dissertation highlights the unique challenges that low-income single women with children, especially women of color, face as mothers. Though the EITC provides opportunity for parents to support an array of family members, it comes at the cost of fewer resources for themselves and their dependent children. I conclude by arguing that policy reform should account for structural inequalities and culturally meaningful expressions of family life.