Can I Change My Taxes if I Forgot a Deduction?

The Internal Revenue Service allows taxpayers to correct mistakes such as missed deductions and other omissions on Form 1040X. You are required to amend returns within three years of filing the original return, or within two years of paying any taxes due. Filing an amended return to include a forgotten deduction does not serve as an extension and will not remove or reduce any late-payment penalties. However, the new deduction may reduce the amount you owe or provide an additional refund.

Step 1

Navigate to the IRS website, select the "Forms & Pubs" tab and choose the necessary forms from the list. Download Form 1040X and Schedule A.

Step 2

Complete Schedule A with your new deduction, as well as the deductions you took on the return you are amended. Your amended total deduction amount will be on line 29.

Step 3

Check the appropriate box at the top of Form 1040X to indicate the year of the tax return you are amending.

Step 4

Fill out the first section of Form 1040X with your name, Social Security number, home address and phone number.

Step 5

Check the appropriate box to indicate your current filing status, even if it is the same as the filing status of the return you are amending.

Step 6

Enter your adjusted gross income from your original return in columns A and C of line 1. Enter 0 in column B.

Step 7

Enter the original deduction amount in column A and the amended deduction amount in column C of line 2. Enter the amount by which your deductions increased or decreased in column B.

Step 8

Fill out the line under the "Income and Deductions," "Tax Liability" and "Payments" headings with amended information. Determine the amount you owe or the refund you are due by filling out lines 17 through 21. Fill out lines 22 and 23 if you want to put any portion of the refund toward estimated taxes for the current year.

Step 9

Subtract the figures in the columns on line 2 from the figures in the columns on line 1 and enter the results on line 3 and line 5.

Step 10

Complete the remainder of the first page of Form 1040X to determine your new tax liability or refund.

Step 11

Explain the changes you made to the return and the reason in Part III on page 2 of Form 1040X. For example, you can simply state that you missed a deduction on your previous return and are filing Form 1040X include it.

Step 12

Sign and date the bottom of page 2. Mail the amended form and any required documentation of the deduction to the regional IRS office in your area.