More than eight million children risk having their health insurance coverage disrupted if federal funding for the Children's Health Insurance Program (CHIP) is not extended beyond 2017. In this study we explored two current policy alternatives: extending federal funding for CHIP or enrolling children in the existing health insurance Marketplace plans. We simulated annual out-of-pocket expenses using detailed health plan data from CHIP and federally facilitated Marketplace plans for a nationally representative cohort of children with chronic conditions, conducting comparisons at four different percentage categories of the federal poverty level. If CHIP funding is not renewed and children with chronic conditions shift to coverage under Marketplace plans, their families face increased annual out-of-pocket expenses ranging from $233 at the lowest income levels to $2,472 at the highest income level of 251-400 percent of poverty. Families with children who have epilepsy, diabetes, or mood disorders may face the highest costs. Cost sharing for prescription drugs (25 percent) and hospitalizations (23 percent) account for much of the difference. Absent enhancements to Marketplace cost-sharing protections, and given recent efforts to repeal the Affordable Care Act, renewing funding for CHIP will provide the greatest financial protections to families of income-eligible children with chronic conditions.