High marginal tax rates can make moving above poverty very difficult for low-income families. These high tax rates result from increasing direct taxes and decreasing transfer payments. A single parent with two children who increases her wages from poverty-level to 150 percent of poverty-level can face a tax rate between 26.6 percent and over 100 percent, depending on which state she lives in. In addition, her marginal tax rate can vary radically, depending on her earning pattern. This paper shows how sensitive marginal tax rates are to assumptions about state of residence, earning patterns, and program participation.