By Elizabeth Rosen for IRS.com
Because mistakes and omissions can sometimes occur, the IRS allows taxpayers to amend their tax returns (and to claim any additional tax breaks or tax refunds).
To amend your return, you must submit IRS Tax Form 1040X (Amended U.S. Individual Income Tax Return) within three years from the date your original tax return was filed, or within two years from the date your tax was paid, whichever is later. Note that a separate 1040X Form must be filed for each tax year you want to amend.
Form 1040X can be used to correct previously filed Forms 1040, 1040A, 1040EZ, 1040NR or 1040NR-EZ. You can also use Form 1040X to make certain elections after the established deadline, to change amounts that were previously adjusted by the IRS or to claim a carryback (due to a loss or unused tax credit).
On the 1040X Form, you will be asked to explain the exact nature of the changes you want to make. Keep in mind, if the changes you are making involve another tax form or schedule, these documents must be attached to your amended return. Also remember that if you are making changes to your federal income tax return, you may also need to adjust/update your state income tax return.