The Affordable Care Act provides tax credits for Marketplace insurance, but before 2021, families with incomes above four times the federal poverty level did not qualify for tax credits and could face substantial financial burdens when purchasing coverage. As a measure of affordability, we calculated potential Marketplace premiums as a percentage of family income among families with incomes of 401-600 percent of poverty. In 2015 half of this middle-class population would have paid at least 7.7 percent of their income for the lowest-cost bronze plan; in 2019 they would have paid at least 11.3 percent of their income. By 2019 half of the near-elderly ages 55-64 would have paid at least 18.9 percent of their income for the lowest-cost bronze plan in their area. The American Rescue Plan Act temporarily expanded tax credit eligibility for 2021 and 2022, but our results suggest that families with incomes of 401-600 percent of poverty will again face substantial financial burdens after the temporary subsidies expire.