In addition to federal income tax collected by the United States, most individual U.S. states collect a state income tax. Some local governments also impose an income tax, often based on state income tax calculations. Forty-two states and many localities in the United States impose an income tax on individuals. Eight states impose no state income tax, and a ninth, New Hampshire, imposes an individual income tax on dividends and interest income but not other forms of income (though it will be phased out by 2027). Forty-seven states and many localities impose a tax on the income of corporations. State income tax is imposed at a fixed or graduated rate on taxable income of individuals, corporations, and certain estates and trusts. These tax rates vary by state and by entity type. Taxable income conforms closely to federal taxable income in most states with limited modifications. States are prohibited from taxing income from federal bonds or other federal obligations. Most states do not tax Social Security benefits or interest income from obligations of that state. In computing the deduction for depreciation, several states require different useful lives and methods be used by businesses. Many states allow a standard deduction or some form of itemized deductions. States allow a variety of tax credits in computing tax. Each state administers its own tax system. Many states also administer the tax return and collection process for localities within the state that impose income tax. State income tax is allowed as an itemized deduction in computing federal income tax, subject to limitations for individuals. Basic principles State tax rules vary widely. The tax rate may be fixed for all income levels and taxpayers of a certain type, or it may be graduated. Tax rates may differ for individuals and corporations. Most states conform to federal rules for determining: gross income, timing of recognition of income and deductions, most aspects of business deductions, characterization of business entities as either corporations, partnerships, or disregarded entities. Gross income generally includes all income earned or received from whatever source with some exceptions. States are prohibited from taxing income from federal bonds or other federal obligations. Most states also exempt income from bonds issued by that state or localities within the state as well as some portion or all of Social Security benefits. Many states provide tax exemption for certain other types of income, which varies widely by state. States