Income tax in the United States dates. Some states permit related corporations to file combined or consolidated returns. Most states and localities imposing income tax require estimated payments where tax exceeds certain thresholds, and require withholding tax on payment of wages. Puerto Rico is treated as a separate taxing entity from the USA; its income tax rates are set independently, and only some residents there pay federal income taxes (though everyone must pay all other federal taxes). The unincorporated territories Guam, American Samoa, and the Virgin Islands also impose income tax separately, under a "mirror" tax law based on federal income tax law. Proposals have been
Income tax in the United States made frequently to change tax laws, often with the backing of specific interest groups. Organizations making such proposals include Citizens for Tax Justice, Americans for Tax Reform, Americans for Tax Fairness, Citizens for an Alternative Tax System, Americans For Fair Taxation, and FreedomWorks. Various proposals have been put forth for tax simplification in Congress including the "Fair Tax Act" and various Flat tax plans. Proponents of a consumption tax argue that the income tax system creates perverse incentives by encouraging taxpayers to spend rather than save: a taxpayer is only taxed once on income spent immediately, while any interest earned