Have you already mailed (on paper or electronically) your Form 1040 for the 2010 tax year but only now noticed you made an error when preparing the return? If you need to correct a mistake on your federal income tax return that you’ve already filed with the IRS, it’s not too late to file another original Form 1040, as opposed to filing an amended return. The last original return filed on or before April 18 will be your official tax return.
Correcting a mistake
Taxpayers cannot file more than one original tax return per tax year, unless the filing deadline for the tax year has not passed. If you have already filed an original Form 1040 with the IRS, but want to correct a mistake you made on the return (such as claiming a deduction or credit you discovered you were entitled to, or removing a credit or deduction you are not qualified to take, changing your filing status, or income, for example) you can actually still file another original return if it is properly filed on or before April 18, 2011 (the filing deadline for this tax season).
Example. You filed your 2010 individual income tax return, Form 1040, on February 1, 2011. But in late February you discovered that you made a mistake on your return. You can file another original return if you file the new return on or before April 18, 2011 (in most other tax years, it is April 15, but due to the Emancipation Day holiday celebrated in Washington, D.C., the deadline for filing returns this year has been moved to April 18). The last original return filed on or before April 18 will be your official tax return. Thus, the last filed return you send before the filing deadline (April 18) is the one that counts as the original return for IRS purposes.
However, if you discover the error on your original return after April 18 has passed, you must file an amended return, Form 1040X, Amended U.S. Individual Income Tax Return, to correct your previously filed return. You cannot file another original Form 1040, since the filing deadline has come and gone. Certain tax elections once made on the original return, however, are irrevocable. Also, any tax not paid with the original return accrues interest. However, as long as a mistake is corrected on an amended return before the original return is audited, penalties are generally waived.