Economist Gary Becker has described educational attainment as the root of economic mobility.[34] Progressive tax rates, while raising taxes on high income, have the goal and corresponding effect of reducing the burden on low income, improving income equality. Educational attainment is often conditional on cost and family income, which for the poor, reduces their opportunity for educational attainment.[35][36] Increases in income for the poor and economic equality reduces the inequality of educational attainment.[37][38] Tax policy can also include progressive features that provide tax incentives for education, such as tax credits and tax exemptions for scholarships and grants.[39][40]