Federal Individual Income Tax Terms: An Explanation

Mark P. Keightley
Analyst in Public Finance

Described in this report are the terms most commonly used when discussing the federal individual income tax. Most of these tax terms are explained in the order that they occur in the process of determining one’s income tax on the Form 1040. Total income is the sum total of all income required to be reported for tax purposes before adjustments to income are made for special types of expenses which Congress has determined should be considered in calculating gross income. These adjustments function like deductions, except that unlike deductions, adjustments are calculated in arriving at adjusted gross income, and thus can be claimed by all taxpayers, not just those who itemize deductions. An exclusion from income refers to an item specifically excluded from determination of gross income. 

Adjusted gross income (AGI) equals gross income less qualifying adjustments to income. It is the income measurement before deductions and personal exemptions are taken into account. Deductions from adjusted gross income are allowed for certain types of expenditures for which income taxation is deemed inappropriate or inadvisable. Deductions function like adjustments and exclusions in their effect on tax liability. In addition to the standard deduction, an additional standard deduction amount is available to certain individuals, for example the blind or elderly. Personal exemptions are allowed for the taxpayer, his or her spouse and each dependent. Exemptions affect tax liability like deductions, adjustments to income, and exclusions. 

Taxable income is adjusted gross income reduced by either the standard deduction (plus the additional standard deduction in some cases) or itemized deductions along with personal exemptions. Taxable income is the base to which the income tax rates are applied to calculate income tax liability. Tax liability is calculated by applying the marginal tax rate and schedule to taxable income. Tax credits are then subtracted from gross tax liability to arrive at a taxpayer’s final tax liability. Hence, tax credits reduce tax liability directly, on a dollar for dollar basis. Tax credits are available to all qualifying taxpayers, whether they itemize deductions or not. Total tax liability is the amount of federal income tax owed by the taxpayer to the federal government. When a taxpayer’s final tax liability exceeds federal taxes withheld, estimated quarterly taxes paid, and certain other credits, then the taxpayer has taxes due and must pay the federal government additional federal income taxes to cover the shortfall. A refund is a payment by the federal government to a taxpayer whose withheld taxes and/or estimated tax payments or refundable credits exceeded his final tax liability.

A copy of the 2011 IRS Form 1040 is included at the end of this report.


Date of Report: June 6, 2012
Number of Pages: 13
Order Number: RL30110
Price: $29.95

Follow us on TWITTER at http://www.twitter.com/alertsPHP or #CRSreports

Document available via e-mail as a pdf file or in paper form.
To order, e-mail Penny Hill Press or call us at 301-253-0881. Provide a Visa, MasterCard, American Express, or Discover card number, expiration date, and name on the card. Indicate whether you want e-mail or postal delivery. Phone orders are preferred and receive priority processing.