Oops! You’ve discovered an error after your tax return has been filed or maybe you need to adjust your 2007 return to include certain non-taxable benefits to reach the $3000 qualifying income level to qualify for an economic stimulus payment. What should you do? You may need to amend your return.

(Note: Generally, the payment of economic stimulus payments is based on the information from your original 2007 federal tax return. However, the only item on an amended return that will affect the economic stimulus payment is when including certain non-taxable benefits not included on the original return. This must be the only reason you were not eligible for the economic stimulus payment on the original return.)

The IRS usually corrects math errors or requests missing forms – such as W-2s or schedules – when processing an original return. In these instances, do not amend your return. However, you should file an amended return if any of the following were reported incorrectly:

• Your filing status
• Your dependents
• Your total income
• Your deductions or credits

Use Form 1040X, Amended U.S. Individual Income Tax Return, to correct a previously filed Form 1040, 1040A, 1040EZ or electronically-filed return. Be sure to enter the year of the return you are amending at the top of Form 1040X. If you are amending more than one tax return, prepare a 1040X for each return and mail them in separate envelopes to the IRS processing center for the area in which you live. The 1040X instructions list the addresses for the centers.

The Form 1040X has three columns. Column A is used to show original or adjusted figures from the original return. Column C is used to show the corrected figures. The difference between the figures in Columns A and C is shown in Column B. There is an area on the back of the form where you explain the specific changes being made on the return and the reason for each change.

If the changes involve another schedule or form, attach it to the 1040X. For example, if you are filing a 1040X because you have a qualifying child and now want to claim the Earned Income Credit, you must attach a Form 1040 Schedule EIC to show the qualifying person's name, year of birth and Social Security number.

If you are filing to claim an additional refund, wait until you have received your original refund before filing Form 1040X. You may cash that check while waiting for any additional refund. If you owe additional tax for 2007, you should file Form 1040X and pay the tax by the April due date to avoid any penalty and interest.

Generally, you must file Form 1040X within three years from the date you filed your original return or within two years from the date you paid the tax, whichever is later, to claim a refund.

Form 1040X and instructions are available at IRS.gov or by calling 800-TAX-FORM (800-829-3676).