How to File an Income Tax Amendment

Amending your return lets you re-file to claim deductions you missed the first time.

Amending your return lets you re-file to claim deductions you missed the first time.

Even with the most careful preparation, the best of us can make a mistake filing our taxes. Whether it's missing out on a deduction that you're entitled to or forgetting to include income you should have paid taxes on, the Internal Revenue Service has a way for you to fix it: filing an amended return. You can amend your return until three years after the original return was filed or two years after the date you paid the tax, whichever is later. Amended returns use IRS Form 1040X, which is available from the IRS website.

Fill out the information required at the top of Form 1040X. Make sure you check the box for the year that you want to amend. Otherwise, the IRS won't know which year you're correcting.

Determine which lines of the Form 1040X you're required to fill out based on what you're amending. The instructions for Form 1040X tell you exactly which lines to fill out. For example, if you need to add income that you forgot to include, you need to fill out lines 1 through 22. If you're just claiming additional nonrefundable credits, you only need to fill out lines 6 through 22.

Complete Columns A, B and C for the lines that you're required to fill out on Form 1040X. Column A shows the original amount from your old return, Column B shows the amount of the change and Column C shows the new amount. Any negative numbers are shown with parenthesis. For example, if you needed to reduce the income reported by $500, report "(500)" in Column B.

Explain the reason for your changes in Part III of Form 1040X. For example, you might say you didn't know you were eligible to claim a credit or deduction, or that you received a corrected W-2 after you filed your original return.

Attach any documents that support your amendment, such as a copy of a new W-2 or receipt documenting a deductible expense, to your amended return. Mail it to the address listed in the Form 1040X instructions based on where you live.

Items you will need

  • IRS Form 1040X

Tip

  • If you're correcting a mistake that causes you to owe additional taxes, filing your amended return sooner rather than later will minimize the interest and late payment penalties you'll owe. Even if you got an extension to file your taxes or made a small and honest mistake, the interest still accrues because you didn't pay on time.

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