This report describes the terms most commonly used when discussing the federal individual income tax. The format of this report is structured to follow the general order of the IRS Form 1040—the form individuals use to determine their income tax. Many taxpayers, however, determine their tax liability with the use of tax preparation software (e.g., TurboTax®) and paid tax preparers, which eliminates the need to be familiar with Form 1040. Therefore, taxpayers who rely on tax preparation software or services may not be familiar with some of the concepts presented in this report. Total income, also sometimes referred to as gross income, is the broadest measure of income used for tax purposes. It is the total of all realized income recognized by the tax law. It is measured net of business expenses but before any other deductions or adjustments. It includes employee compensation such as wages, salaries, and tips; taxable interest and dividend income; business and farm income (net of expenses); realized capital gains; income from rents, royalties, trusts, estates, and partnerships; and taxable pensions and annuities. Gross income does not include income explicitly excluded from tax. An exclusion is an item of income that is not included as income for tax purposes because the tax code explicitly excludes—or exempts—it from taxation. Examples of items of income which are exempt from federal income taxation and, hence, excluded from gross income, are state and local bond interest income, public assistance (welfare), small gifts, employer contributions for health care, and employer-provided contributions to retirement plans. Social security and railroad retirement income may or may not be excluded from income subject to tax. The taxability of social security and railroad retirement depends on the amount of other income the taxpayer receives. Other forms of income excluded from taxation are a clergy member's tax-free housing allowance, qualified foster care payments, and qualified scholarship and fellowship grants. Under certain conditions, a taxpayer can exclude a limited amount of disability pay such as workers' compensation. Except for tax-exempt interest, exclusions generally are not required to be reported to the Internal Revenue Service. A taxpayer's gross income is listed on line 22 of the Form 1040 found in Appendix A . The individual components of a taxpayer's gross income are listed on lines 7 to 21. Exclusions are not listed explicitly on the Form 1040. Adjustments to income, also known as above-the-line deductions, are allowed for certain payments made by the taxpayer and are generally related to the earning of income. These payments are deducted from gross income in arriving at adjusted gross income. Payments that may qualify for an above-the-line deduction may include contributions to Keogh or traditional (but not Roth) individual retirement accounts (IRAs), forfeited penalties on early withdrawals of savings, interest paid on student loans, moving expenses, and alimony payments. Adjustments to income function similarly to deductions. However, unlike deductions, adjustments are made to arrive at adjusted gross income, and hence can be claimed by all qualified taxpayers, whether or not they use the standard deduction amount or have itemized deductions (see " Deductions "). The sum of a taxpayer's adjustments to income is listed on line 36 on the Form 1040. The individual components of a taxpayer's total adjustments to income are listed on lines 23 to 35. Adjusted gross income (AGI) is equal to a taxpayer's total income minus adjustments to income (see previous two sections). AGI is the basic measure of income under the federal income tax and is the income measurement before deductions and personal exemptions are taken into account. AGI is commonly used as the base for computing many of the limits under the tax law, such as those on the itemized deduction for medical and dental expense and miscellaneous itemized deductions. A taxpayer's adjusted gross income is listed on line 37 of the Form 1040 and is carried over to line 38 so that the taxpayer may continue onto page 2 of the Form 1040. Deductions from adjusted gross income are allowed for certain types of expenditures of income. Deductions may be claimed in one of two ways. First, taxpayers can choose to itemize (explicitly list) their deductible expenses. Itemized deductions are allowed for many purposes, including certain medical expenses; state and local property taxes, income (or sales) taxes, and a few other taxes; home mortgage interest, points, and limited amounts of other interest paid (but not personal interest); contributions to charitable organizations; certain casualty and theft losses less $100 per event; investment expenses; tax preparation fees; certain unreimbursed employee business expenses; and a few other "miscellaneous" expenses. Alternatively, a taxpayer can choose to claim the so-called standard deduction, which was intended to reduce the complexity of paying taxes. The standard deduction varies depending on filing status (single, married filing jointly, head of household), whether the taxpayer is over 65, and whether the taxpayer is blind. For 2016 the standard deductions were as follows: $12,600 for married taxpayers filing jointly or qualified widow(er)s; $6,300 for single taxpayers; and $9,300 for taxpayers who qualify as the head of a household. The standard deductions for those who are 65 or older and for those who are legally blind are increased by $1,550 if single or head of household and $1,250 if married filing jointly. These increases apply per classification. Thus, a 70-year-old blind and single taxpayer would be eligible for a $3,100 increase in his or her standard deduction. These amounts are adjusted annually for inflation. Only individuals with deductions that can be itemized in excess of the standard deduction find it worthwhile to itemize. These tend to be taxpayers in the middle to high income ranges. For the 2014 tax year (the most recent data), approximately 30% of taxpayers itemized their deductions. Whichever deduction the taxpayer claims—itemized or standard—the deduction amount is subtracted from AGI. Deductions function like adjustments and exclusions in their effect on tax liability. Deductions reduce a taxpayer's tax liability, but only by a percentage of the amount deducted. An individual in the 35% tax bracket would receive a reduction in taxes of $35 for each $100 deduction while an individual in the 25% tax bracket would receive a reduction in taxes of $25 for each $100 deduction. Hence, the same deduction can be worth different amounts to different taxpayers depending on their marginal tax bracket. More simply stated, the tax savings from deductions are generally equal to the taxpayer's tax rate times the amount of the deduction. So higher-income taxpayers typically benefit more than lower-income taxpayers from deductions. A taxpayer's standard or total itemized deductions are listed on line 40 of the Form 1040. The individual components of the itemized deduction are listed on lines 1 to 28 on Schedule A to Form 1040 in Appendix A . Before calculating total income, personal exemptions are allowed for the taxpayer, his or her spouse (if married and filing a joint return), and each dependent. If a taxpayer's AGI is less than $155,650 each exemption claimed reduces income subject to taxation by $4,050 for tax year 2016 (this amount is adjusted for inflation annually). If a taxpayer's AGI is greater than $155,650, then they must reference the Worksheet for Determining the Deduction for Exemptions on page 23 of IRS Publication 501. The personal exemptions combined with the standard deduction amount are designed to remove low-income households from the tax rolls, and exempt a minimum level of income from taxation for other families. The value of the personal exemptions is reduced or eliminated for certain taxpayers with a relatively high AGI. The number of exemptions a taxpayer claims is listed on line 6 of the Form 1040. The value to the taxpayer of claiming this particular number of exemptions is found on line 42. Taxable income, the narrowest measure of income used on the income tax return, is equivalent to adjusted gross income reduced by either the standard deduction or itemized deduction and the personal exemption. Taxable income is the base upon which the income tax rates are applied to calculate income tax liability. Taxable income is listed on line 43 of the Form 1040. Tax liability, also sometimes referred to as gross tax liability, is a taxpayer's tax liability prior to the subtraction of tax credits. For most taxpayers, gross tax liability is equal to regular income tax liability, which is calculated by applying the marginal tax rate schedule to taxable income. The structure of the marginal tax rate schedule is progressive, which means higher-earning taxpayers face higher tax rates on the last dollar that they earn. To understand how the marginal tax structure is applied, consider the 2016 marginal tax rate schedule provided in Appendix B . The 2016 tax schedule shows the various tax rates and income ranges to which those rates are applied. A married couple with a taxable income of $80,000 would fall into the 25% tax bracket. This means that the first $18,550 of their taxable income would be taxed at a rate of 10%, their next $56,750 of income would be taxed at 15%, and the last $4,700 of income would be taxed at 25%. A small fraction of taxpayers (4.8% in 2016) must also account for the alternative minimum tax (AMT) when computing their gross tax liability. The AMT is calculated in the following manner. First, an individual adds back certain tax deductions and tax preference items to taxable income. This amount then becomes the AMT tax base. Next, a basic exemption is allowed and subtracted from the AMT tax base. A two-tiered tax rate structure of 26% and 28% is then assessed against the remaining AMT tax base to determine the AMT liability. If the AMT liability exceeds a taxpayer's regular income liability a taxpayer must add the difference between the two to his or her regular income tax liability to arrive at gross tax liability.