Proposed changes to broad-based categorical eligibility in the Supplemental Nutrition Assistance Program (SNAP) will affect the National School Lunch Program, which uses SNAP to determine free lunch eligibility for both individual students and schools. The administration has suggested as many as 982,000 students could be affected, but we find compelling evidence that the potential nutritional and financial impact of this rule change is greater than originally reported because of how the changes would affect schools that provide free lunch for all students through the Community Eligibility Provision (CEP). In this brief, we estimate that 142,000 students are at schools that would lose CEP eligibility, and 1.05 million students are at schools that would lose full reimbursement for free lunches, potentially putting schools’ CEP status at risk.