If subsequent to filing your tax return, you discover that errors were made, you should file an amended tax return to correct these errors. Naturally, this corrective information will alter your tax calculations. The following are some of the typical errors you can make on your tax return:
• You did not report all of your income. For example, you received a W-2 with additional income, which arrived after you filed your original return.
• You claimed deductions or credits on your original tax return that you were not eligible for, and need to remove them.
• Conversely, you subsequently discovered that you did not claim all the deductions or credits you should have claimed, and need to include them.
• You need to make a correction to your filing status.
You should not file an amended return if you are only correcting mathematical errors, as the IRS computers will check your math and correct any errors in the calculation. Mathematical errors are errors made in adding or subtracting items on your tax return.
To file an amended return, you must use Form 1040X, Amended U.S. Individual Income Tax Return.
The following rules relate to filing amended returns:
• Form 1040X cannot be filed electronically, and must be mailed in as a paper return.
• You must file a separate Form 1040X for each year being amended.
• An amended return will usually result in either additional tax due, or a refund owed to you. If you are due a refund, interest might be paid on it.
• You must file Form 1040X within three years after the date you filed the original return, or within two years after the date you paid the tax, whichever is later.
• If you did not file an original return when due, generally you can claim a refund by filing a return within three years from the date the tax was paid.
Note that if you file an amended federal return, you should also amend your state tax return.