The most lasting impact and significant change of the Act was indexing the tax code parameters for inflation, Even after the Act was passed, federal individual income tax receipts never fell below 8.05% of the GDP. Combined with indexing, that eliminated the need for future tax cuts to address it. The first 5% of the 25% total cuts took place beginning on October 1, 1981. An additional 10% began on July 1, 1982, followed by a third decrease of 10% starting July 1, 1983. As a result of that and other tax acts in the 1980s, the top 10% were paying 57.2% of total income taxes by 1988, up from 48% in 1981, but the bottom 50% of earners' share dropped from 7.5% to 5.7% during the same period. Much of the increase can be attributed to the decrease in capital gains taxes. Also, the ongoing recession and high unemployment contributed to stagnation among other income groups until the mid-1980s. Under ERTA, marginal tax rates dropped (top rates from 70% to 50%)and capital gains tax was reduced from 28% to 20%. Revenue from capital gains tax increased 50% from $12.5 billion in 1980 to over $18 billion in 1983. which eventually lowered the deficits. After peaking in 1986 at $221 billion the deficit fell to $152 billion by 1989. The Office of Tax Analysis estimated that the act lowered federal income tax revenue by 13% from what it would have been in the bill's absence. Canada, which had adopted the indexing of income tax in the early 1970s, saw deficits at similar and even larger levels to the United States in the late 1970s and the early 1980s. The non-partisan
Congressional Research Service (in the
Library of Congress) issued a report in 2012 analyzing the effects of tax rates from 1945 to 2010. It concluded that top tax rates have no positive effect on economic growth, saving, investment, or productivity growth; however, the reduced top tax rates increase income inequality: In the words of Thomas L. Hungerford, "The reduction in the top tax rates appears to be uncorrelated with saving, investment, and productivity growth. The top tax rates appear to have little or no relation to the size of the economic pie. However, the top tax rate reductions appear to be associated with the increasing concentration of income at the top of the income distribution." Tax revenue from the wealthy dropped, and much of the increased wealth collected was at the top of the tax bracket. ==References==