In the aftermath of the 1997 Asian Financial Crisis, South Korea faced a paradox familiar to many emerging economies: a shrinking tax base colliding with an expanding fiscal need. With nearly a quarter of GDP circulating in the shadow economy and cash-based self-employment operating beyond the reach of the National Tax Service, the government turned to an unconventional solution. Rather than intensifying audits on sellers, it redesigned the incentive structure for buyers, recognizing that consumers, properly motivated, could do the work of tax administration. The strategy leveraged three converging conditions: acute post-crisis fiscal pressure, a maturing ICT infrastructure, and a political moment in which reform carried the legitimacy of national recovery.The result was a two-stage experiment that would transform one of Asia's most cash-dependent societies into one of its most transaction-transparent. The Credit Card Income Deduction Program in 1999 rewarded earned income taxpayers for shifting consumption into traceable channels, and the Cash Rceipt System of 2005 extended the same logic into remaining cash transactions. Nearly two decades later, these programs remain embedded in Korea's tax code, having weathered repeated sunset debates. Yet their legacy also includes a credit card delinquency crisis, a regressive distributional pattern, and a political lock-in that has made reform difficult.