In 2021 Congress expanded the Child Tax Credit (CTC), one of the largest US economic supports for working families with proven benefits for health. Information on CTC take-up among eligible families is lacking. Understanding barriers to anti-poverty programs is an urgent policy issue, as low take-up is an established barrier to health equity. Among a longitudinal cohort of primarily Latino and Black California families with low income (N = 380), we used data from individuals’ 2019 and 2021 tax returns to compare CTC take-up (i.e., receipt among eligible individuals) pre- and post-program expansion. We also compared CTC take-up with take-up of the Earned Income Tax Credit (EITC), a similar US anti-poverty tax policy. We also compared take-up rates by income, age, language, and education. CTC take-up was higher in 2021 (79 %) compared with 2019 (44 %). EITC take-up was relatively unchanged. CTC and EITC take-up was lower among marginalized groups across both periods. CTC take-up increased in 2021 among this sample of low-income households, yet disparities persisted. Optimizing potential benefits of-and removing barriers to-the CTC and EITC could further reduce poverty and improve health equity. This study provides policymakers with timely evidence to inform program design to address persistent health and social inequities.