It looks like in practice the most generous of these programs are not accessible to most working poor, so the charts here are more theoretical than practical. It also doesn't address income tax-free earnings (traditional 401k and IRA) - it seems like those generally don't count against your eligibility for programs and could shelter ~25k or more for the self-employed. Not that I imagine most people actually near poverty are maxing out their retirement accounts, even if it theoretically costs them nothing or even gains them value.