U.S. generally accepted accounting principles. Since only publicly traded companies are required to prepare financial statements, many non-public companies opt to keep their financial records under tax rules. Corporations that present financial statements using other than tax rules must include a detailed reconciliation of their financial statement income to their taxable income as part of their tax returns. Key areas of difference include depreciation and amortization, timing of recognition of income or deductions, assumptions for cost of goods sold, and certain items (such as meals and entertainment) the tax deduction for which is limited. Reporting under self-assessment system Income taxes in the United States are self-assessed by taxpayers by filing required tax returns. Taxpayers, as well as certain non-tax-paying entities, like partnerships, must file annual tax returns at the federal and applicable state levels. These returns disclose a complete computation of taxable income under tax principles. Taxpayers compute all income, deductions, and credits themselves, and determine the amount of tax due after applying required prepayments and taxes withheld. Federal and state tax authorities provide preprinted forms that must be used to file tax returns. IRS Form 1040 series is required for individuals, Form 1120 series for corporations, Form 1065 for partnerships, and Form 990 series for tax exempt organizations. The state forms vary widely, and rarely correspond to federal forms. Tax returns vary from the two-page (Form 1040EZ) used by nearly 70% of individual filers to thousands of pages of forms and attachments for large entities. Groups of corporations may elect to file consolidated returns at the federal level and with a few states. Electronic filing of federal and many state returns is widely encouraged and in some cases required, and many vendors offer computer software for use by taxpayers and paid return preparers to prepare and electronically file returns. Capital gains tax Individuals and corporations pay U.S. federal income tax on the net total of all their capital gains. The tax rate depends on both the investor's tax bracket and the amount of time the investment was held. Short-term capital gains are taxed at the investor's ordinary income tax rate and are defined as investments held for a year or less before being sold. Long-term capital gains, on dispositions of assets held for more than one year, are taxed at a lower rate. Payroll taxes In the United States, payroll taxes are assessed by the federal government, many states,