State income tax

Most individual U.S. states collect a state income tax in addition to federal income tax. The two are separate entities. Some local governments also impose an income tax, often based on state income tax calculations. Forty-three states and many localities in the United States may impose an income tax on individuals. 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. The rates vary by state. Taxable income conforms closely to federal taxable income in most states, with limited modifications. The states are prohibited from taxing income from federal bonds or other obligations. Most do not tax Social Security benefits or interest income from obligations of that state. Several states require different useful lives and methods be used by businesses in computing the deduction for depreciation. 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 a deduction in computing federal income tax, subject to limitations for individuals.

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 generally includes all income earned or received from whatever source, with exceptions. The states are prohibited from taxing income from federal bonds or other 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. The states imposing an income tax uniformly allow reduction of gross income for cost of goods sold, though the computation of this amount may be subject to some modifications.

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