The Affordable Care Act (ACA) was designed to increase health insurance coverage while limiting the disruption to individuals with existing sources of insurance coverage, particularly those with employer-sponsored insurance (ESI). To limit disruption to those with coverage, the ACA implements the employer mandate, which requires firms with more than 50 employees to offer health insurance or face penalties, and the individual "affordability firewall," which limits subsidies to individuals lacking access to alternative sources of coverage that are "affordable." This report examines the policy impacts of the affordability firewall and investigates two potential modifications. Option 1, which is the "entire family" scenario, involves allowing an exception to the firewall for anyone in a family where the family ESI premium contribution exceeds 9.5 percent of the worker's household income. In Option 2, the "dependents only" scenario, only dependents (and not the worker) become eligible for Marketplace subsidies when the ESI premium contribution exceeds 9.5 percent of the worker's household income. Relative to the ACA, RAND researchers estimate that nongroup enrollment will increase by 4.1 million for Option 1 and by 1.4 million for Option 2. However, the number without insurance only declines by 1.5 million in Option 1 and 0.7 million in Option 2. The difference between the increase in nongroup enrollment and the decrease in uninsurance is primarily due to ESI crowd-out, which is more pronounced for Option 1. Researchers also estimated that about 1.3 million families who have ESI and unsubsidized nongroup coverage under current ACA policy would receive Marketplace subsidies under the alternative affordability firewall scenarios. For these families, health insurance coverage would become substantially more affordable; these families' risk of spending at least 20 percent of income on health care would drop by more than two thirds. We additionally estimated that federal spending will increase by $8.9 billion and $3.9 billion for Options 1 and 2, respectively, relative to the ACA.