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
Working Tax Credit significant levels of overpayments. In order to reduce the overpayment problem, the income disregard was raised tenfold from £2,500 to £25,000 with effect from 2006/07. Income for tax credit purposes is "in principle" assessed similarly to UK income tax. Thus 'income' (c/f 'taxable income') consists of what the individual receives from gross earned and unearned sources—less allowances for 'expenditures' that would reduce that income. But, unlike income tax, tax credits measure income based on family 'household', rather than the individuals within. Also the effect of "income disregard" —to mask large annual increases in resources from reassessment— weakens comparisons with a