Key PointsQuestionWere 2021 Expanded Child Tax Credit (ECTC) monthly payments associated with changes in adult overall health or household food security?FindingsIn this repeated cross-sectional study using nationally representative survey data from 39 479 respondents and a difference-in-differences design, eligibility for ECTC payments was associated with improved overall adult health and household food security.MeaningThe results of this cross-sectional study suggest that the COVID 19–era policy of ECTC monthly payments may have been associated with improved health and nutrition in adults in eligible households.