Form 1040X is only filed after you have filed your original return. Generally, Form 1040X must be filed within 3 years after the date you filed the original return or within 2 years after the date you paid the tax, whichever is later.

If you discover an error after your return has been mailed, you may need to amend your return. The service center will usually correct errors in math or request forms (such as W-2s) or schedules left out. In these instances, do not amend your return! However, do file an amended return if any of the following were reported incorrectly: your filing status your total income your deductions or credits

If you are filing to claim an additional refund, wait until you have received your original refund (you may cash that check). To avoid penalty and interest, if you owe additional tax for 2004, you should file Form 1040X and pay the tax by April 16, 2005. 1040X has three columns. Column A is used to show original or adjusted figures from the original return. Column C is used to show the correct figures. The difference between the figures in Columns A and C is shown in Column B. There is an area on the back of the form where you explain the specific changes being made on the return and the reason for each change. If the changes involve another schedule or form, attach it to the 1040X. For example, if you are filing a 1040X because you have a qualifying child and now want to claim the Earned Income Credit, you must attach a Schedule EIC to show the qualifying persons name and social security number. Be sure to enter the year of the return you are amending. Please Note: Your state tax liability may be affected by a change made on your federal return.

You will be notified by the Internal Revenue Service of any balance due including any interest and penalties that may apply. You may pay the amount you owe at the time you mail your form 1040x. Make all checks out to the Department of the Treasury include the primary social security number and the year for which the payment is to be applied. Do not combine payments.