In this policy memo, Kevin Welner explains how voucher advocates inadvertently paved the way for Democrats' plan to skirt a punitive element of the tax law passed by Congress in December 2018. Republican voucher advocates developed, spread, and defended the legality of a system of dollar-for-dollar tax credits for donations to private voucher-granting organizations as a way to evade prohibitions in state constitutions against spending public state money on religious schools.