For tax purposes, an alien is an individual who is not a U.S. citizen. Aliens are classified as nonresident aliens and resident aliens. This publication will help you determine your status and give you information you will need to file your U.S. tax return. Resident aliens generally are taxed on their worldwide income, the same as U.S. citizens. Nonresident aliens are taxed only on their income from sources within the United States and on certain income connected with the conduct of a trade or business in the United States.

Table A, Where To Find What You Need To Know About U.S. Taxes, provides a list of questions and the chapter or chapters in this publication where you will find the related discussion.

Answers to frequently asked questions are presented in the back of the publication.

The information in this publication is not as comprehensive for resident aliens as it is for nonresident aliens. Resident aliens are generally treated the same as U.S. citizens and can find more information in other IRS publications.

IRA deduction expanded. You may be able to take an IRA deduction if you were covered by a retirement plan and your 2010 modified AGI is less than $66,000 ($109,000 if married filing jointly or qualifying widow(er)). If your spouse was covered by a retirement plan, but you were not, you may be able to take an IRA deduction if your 2010 modified AGI is less than $177,000.

Repayment of first-time homebuyer credit. If you claimed the first-time homebuyer credit for a home you bought in 2008, you generally must begin repaying it in 2010. See Form 5405 for details.

Personal exemption and itemized deduction phaseouts ended. For 2010, taxpayers with adjusted gross income above a certain amount will no longer lose part of their deduction for personal exemptions and itemized deductions. Under current law, these phaseouts will resume in 2013.

Earned income credit (EIC). You (if you are a resident alien) may be able to take the EIC if:

The maximum AGI you can have and still get the credit also has increased. You may be able to take the credit if your AGI is less than the amount in the above list that applies to you. The maximum investment income you can have and get the credit is still $3,100.

Personal casualty and theft loss limit reduced. Each personal casualty or theft loss is limited to the excess of the loss over $100 (instead of $500).

Dividend equivalent payments. All dividend equivalent payments made after September 13, 2010, are U.S.-source dividends. See chapter 2 for more information.

Guarantee of indebtedness. Certain amounts received directly or indirectly, for the provision of a guarantee of indebtedness issued after September 27, 2010, are U.S. source income. See chapter 2 for more information.

Expired tax benefits. The following tax benefits have expired and are not available for 2010.

Personal exemption increased. For tax years beginning in 2011, the personal exemption amount is increased to $3,700.

Temporary decrease in employee's share of payroll tax. Social security tax will be withheld from an employee's wages at the rate of 4.2% (down from 6.2%) up to the social security wage limit of $106,800. There will be no change to Medicare withholding.The same reduction applies to net earnings from self-employment—the temporary rate will be 10.4% (down from 12.4%) up to the social security wage limit of $106,800.

Third party designee. You can check the “Yes” box in the “Third Party Designee” area of your return to authorize the IRS to discuss your return with a friend, family member, or any other person you choose. This allows the IRS to call the person you identified as your designee to answer any questions that may arise during the processing of your return. It also allows your designee to perform certain actions such as asking the IRS for copies of notices or transcripts related to your return. Also, the authorization can be revoked. See your income tax return instructions for details.

Change of address. If you change your mailing address, be sure to notify the Internal Revenue Service using Form 8822, Change of Address.

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.