Background Heart failure (HF) poses a major public health burden in the United States. We examined the burden of out‐of‐pocket healthcare costs on patients with HF and their families. Methods and Results In the Medical Expenditure Panel Survey, we identified all families with ≥1 adult member with HF during 2014 to 2018. Total out‐of‐pocket healthcare expenditures included yearly care‐specific costs and insurance premiums. We evaluated 2 outcomes of financial toxicity: (1) high financial burden—total out‐of‐pocket healthcare expense to postsubsistence income ratio of >20%, and (2) catastrophic financial burden with the ratio of >40%—a bankrupting expense defined by the World Health Organization. There were 788 families in the Medical Expenditure Panel Survey with a member with HF representing 0.54% (95% CI, 0.48%–0.60%) of all families nationally. The overall mean annual out‐of‐pocket healthcare expenses were $4423 (95% CI, $3908–$4939), with medications and health insurance premiums representing the largest categories of cost. Overall, 14% (95% CI, 11%–18%) of families experienced a high burden and 5% (95% CI, 3%–6%) experienced a catastrophic burden. Among the two‐fifths of families considered low income, 24% (95% CI, 18%–30%) experienced a high financial burden, whereas 10% (95% CI, 6%–14%) experienced a catastrophic burden. Low‐income families had 4‐fold greater risk‐adjusted odds of high financial burden (odds ratio [OR] , 3.9; 95% CI, 2.3–6.6), and 14‐fold greater risk‐adjusted odds of catastrophic financial burden (OR, 14.2; 95% CI, 5.1–39.5) compared with middle/high‐income families. Conclusions Patients with HF and their families experience large out‐of‐pocket healthcare expenses. A large proportion encounter financial toxicity, with a disproportionate effect on low‐income families.