How to Amend a Return to Increase Deductions & Claim Dependents

Everyone makes mistakes, and with the complexities of the U.S. federal income tax code, it's not unlikely they could occur when filing your taxes. If you discover you've made a mistake that resulted in you paying more taxes than you actually owe -- for example, you discovered additional deductions or neglected to include a dependent -- you can correct the error by filing an amended return.

Gather your tax document, including your original tax return and all supporting documentation, such as your W2. Go to the IRS website and download the appropriate forms for the year you are amending. The IRS allows you to amend your taxes for up to three years prior to the due date of your last return, so input the right changes on the right form. For example, if you need to add additional mortgage interest to your 2010 tax return, you'll need the current year Form 1040X and the 2010 Schedule A.

Complete the top portion of Page 1 of Form 1040X. Check the tax year you wish to amend. You must submit a new Form 1040X for each year you need to amend. Fill in your name, address, phone number and Social Security number. If you're amending a joint return, include your spouse's name and Social Security number. Check the appropriate filing status box.

Complete the portions of Form 1040X that relate to the changes you need to make. Form 1040X can be used for a number of different purposes, so you don't need to complete every line. Make entries only where changes are needed. On any additional dependents, make the appropriate changes on Lines 1–31, and ensure that the names of your dependents match their Social Security numbers. If you need to update your itemized deductions or standard deduction, make the appropriate changes on Lines 1–22. Use Part III on Page 2 to explain the changes you've made.

Sign and date your amended return. If you originally filed a joint return, or you're changing your filing status to a joint return, your spouse must also sign and date the form. Assemble your amended return along with any schedules and appropriate documentation. Mail your completed amended return to the IRS. As of the 2011 tax year, you could not file an amended return electronically.