> Nobody tell this guy about the Earned Income Tax Credit. Let him think he discovered it.

I know about the EITC, but the ETIC net of benefit clawbacks still presents a high marginal rate. Then the EITC itself gets clawed back at its own threshold, imposing a small region of high marginal rates. (The EITC itself is also rather paltry for filers without children.)

Additionally, the US tax system is ill-structured to really implement this. If you're trying to operate on the "under-the-table cash payments for day labour" margin, a system that depends on filing one's taxes to receive a refund later is not exactly hassle-free.