Economic insecurity is a risk factor for intimate partner homicide (IPH). The Earned Income Tax Credit (EITC) is the largest cash transfer programme to low-income working families in the USA. We hypothesised that EITCs could provide financial means for potential IPH victims to exit abusive relationships and establish self-sufficiency. We conducted a national, quasiexperimental study of state EITCs and IPH rates in 1990–2016 using a difference-in-differences approach. The national rate of IPH decreased from 1.9 per 100 000 adult women in 1990 to 1.3 per 100 000 in 2016. We found no statistically significant association between state EITC generosity and IPH rates (coefficient indicating change in IPH rates per 100 000 adult female years for additional 10% in amount of state EITC, measured as the percentage of federal EITC: 0.02, 95% CI –0.03 to 0.08). Financial control associated with abuse and current EITC eligibility rules may prevent potential IPH victims from accessing the EITC.