In general, the United States federal income tax is progressive, as rates of tax generally increase as taxable income increases, at least with respect to individuals that earn wage income. As a group, the lowest earning workers, especially those with dependents, pay no income taxes and may actually receive a small subsidy from the federal government (from child credits and the Earned Income Tax Credit). "Progressivity" as it pertains to tax is usually defined as meaning that the higher a person's level of income, the higher a tax rate that person pays. In the mid-twentieth century, marginal tax rates (the rate applied to the last bit of income) in the United States and United Kingdom exceeded 90%. As recently as the late 1970s, the top marginal tax rate in the U.S. was 70%. In the words of Piketty and Saez, "... the progressivity of the U.S. federal tax system at the top of the income distribution has declined dramatically since the 1960s". They continue, "... the most dramatic changes in federal tax system progressivity almost always take place within the top 1 percent of income earners, with relatively small changes occurring below the top percentile." Progressivity, then, is a complex topic which does not lend itself to simple analyses. Given the "flattening" of tax burden that occurred in the early 1980s, many commentators note that the general structure of the U.S. tax system has begun to resemble a partial consumption tax regime. Tax distribution As of 2010, there were 118.7 million taxpaying households in the United States. The median marginal federal income tax rate is 15%. In addition, there are numerous other federal taxes and transfers that affect one's net tax burden, including federal payroll taxes (both employer share and employees share), Corporate Income Taxes, Excises Taxes, Estate and Gift Taxes, Customs Duties and Miscellaneous Receipts. According to the Congressional Budget Office (CBO), the median taxpayer in the United States has had an effective overall federal tax burden that has declined from 19.14% of Before-Tax Income in 1979 to 11.20% of Before-Tax Income as of 2010. When simply comparing Market Income to After Tax Income, due to Government Transfers the Net Federal Tax burden of the median taxpayer has declined from 13.94% in 1979 to -8.76% in 2010 - this metric became negative for the first time in 2008. The CBO report in 2013 shows the share of federal taxes