Can an Overlooked Past Tax Deduction Be Claimed Presently?

You can correct mistakes on your federal income tax return by filing Form 1040X.

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You aren't automatically out of luck if you've discovered that you missed a deduction after you filed your federal income tax returns. You can claim a tax deduction that you overlooked on your tax return for the present year and for previous years. You must file the proper form, however, and there are deadlines involved. Consult with a financial or tax professional with questions concerning your individual circumstances.

Commonly Missed Deductions

American tax laws are among the most complex, and the Internal Revenue Service makes changes to the tax code every year, some of which are significant. Missing one-time tax deductions is a common oversight made by taxpayers, especially diligent taxpayers who file their returns early in the year. Even professional tax preparers often miss one-time deductions. Other tax deductions taxpayers often miss are travel expenses to and from receiving medical treatment, home improvements that increase energy efficiency and mortgage refinancing points. Some mistakes are not even discovered until taxpayers file the following year's returns.

Filing Form 1040X

If you make a mistake on your federal income tax return, including missing a significant tax deduction, you must file Form 1040X to correct the error. The form and instructions are available to download from the IRS website. Include the year for which you are making the correction on the form, along with any schedules that you did not file with your original return. You don't need to file new copies of your original schedules or W-2 forms, however. Wait until you've received your original refund before filing Form 1040X.

Receiving Your Refund

You may complete Form 1040X on your computer and save the completed form for your records. However, once you complete Form 1040X, you must print out and file one copy of the completed form, along with copies of any additional schedules, by mail. The IRS will issue a paper check for your additional refund; you cannot specify direct deposit for refunds issued from filing Form 1040X. As a result, the normal wait time for the IRS to process your return ranges from eight to 12 weeks.


Indicate on form 1040X why you are making changes from your original return, noting the line number on the return. You must print a separate Form 1040X for each tax year for which you are submitting a corrected return. Each return must be mailed in its own envelope. The deadline for filing Form 1040X is three years from the date you filed your original return, or two years from the date you paid any taxes on your original return, whichever is later. Tax returns filed before the original due date, notwithstanding extensions, are considered to be filed on the due date. You may also need to file an amended state income tax return.

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About the Author

Chris Blank is an independent writer and research consultant with more than 20 years' experience. Blank specializes in social policy analysis, current events, popular culture and travel. His work has appeared both online and in print publications. He holds a Master of Arts in sociology and a Juris Doctor.

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