Who must file. In some cases, the amount of income you can receive before you must file a tax return has increased. Table 1 shows the filing requirements for most taxpayers.

Exemption amount. The amount you can deduct for each exemption has increased. It was $3,700 for 2011. It is $3,800 for 2012.

Standard deduction increased. The standard deduction for some taxpayers who do not itemize their deductions on Schedule A of Form 1040 is higher for 2012 than it was for 2011. The amount depends on your filing status. You can use the 2012 Standard Deduction Tables near the end of this publication to figure your standard deduction.

Future developments. Information about any future developments affecting Publication 501 (such as legislation enacted after we release it) will be posted at www.irs.gov/pub501.

Taxpayer identification number for aliens. If you are a nonresident or resident alien and you do not have and are not eligible to get a social security number (SSN), you must apply for an individual taxpayer identification number (ITIN). Your spouse also may need an ITIN if he or she does not have and is not eligible to get an SSN. See Form W-7, Application for IRS Individual Taxpayer Identification Number. Also, see Social Security Numbers for Dependents , later.

Photographs of missing children. The Internal Revenue Service is a proud partner with the National Center for Missing and Exploited Children. Photographs of missing children selected by the Center may appear in this publication on pages that would otherwise be blank. You can help bring these children home by looking at the photographs and calling 1-800-THE-LOST (1-800-843-5678) if you recognize a child.

This publication discusses some tax rules that affect every person who may have to file a federal income tax return. It answers some basic questions: who must file; who should file; what filing status to use; how many exemptions to claim; and the amount of the standard deduction.

Who Must File explains who must file an income tax return. If you have little or no gross income, reading this section will help you decide if you have to file a return.

Who Should File helps you decide if you should file a return, even if you are not required to do so.

Filing Status helps you determine which filing status to use. Filing status is important in determining whether you must file a return and whether you may claim certain deductions and credits. It also helps determine your standard deduction and tax rate.

Exemptions, which reduce your taxable income, are discussed in Exemptions .

Exemptions for Dependents explains the difference between a qualifying child and a qualifying relative. Other topics include the social security number requirement for dependents, the rules for multiple support agreements, and the rules for divorced or separated parents.

Standard Deduction gives the rules and dollar amounts for the standard deduction — a benefit for taxpayers who do not itemize their deductions. This section also discusses the standard deduction for taxpayers who are blind or age 65 or older, as well as special rules that limit the standard deduction available to dependents. In addition, this section helps you decide whether you would be better off taking the standard deduction or itemizing your deductions.

How To Get Tax Help explains how to get tax help from the IRS.

This publication is for U.S. citizens and resident aliens only. If you are a resident alien for the entire year, you must follow the same tax rules that apply to U.S. citizens. The rules to determine if you are a resident or nonresident alien are discussed in chapter 1 of Publication 519, U.S. Tax Guide for Aliens.