Democrats claim to have a monopoly on caring for the poor and suffering, and this week the left is portraying a GOP health-care bill as an attack on society’s vulnerable. So check out the data on how ObamaCare is a tax on some low-income families.

IRS data offers insight into who paid the law’s individual mandate penalty in 2015 for not buying health insurance, the latest year for which figures are available. Spoiler alert: The payers aren’t Warren Buffett or any of the other wealthy folks Democrats say they want to tax....