If an error is made on a tax return, an amended return can be filed after the original return is filed to correct the error. Taxpayers should file an amended return if the filing status, dependent information, income, or deductions or credits were reported incorrectly.

File an amended return. Form 1040X, Amended U.S. Individual Income Tax Return, is filed to amend a previously filed Form 1040, 1040A, or 1040EZ. The taxpayer must indicate on Form 1040X the year of the return being amended. Taxpayers who are filing amended returns for multiple years must prepare a Form 1040X for each return and mail each return separately. Amended returns must be filed by paper.

Form 1040X is designed so the taxpayer can indicate the original amount filed for each category of income, deductions, and credits, as well as the corrected amount. A simple calculation will reflect the difference in the amounts originally filed and the corrected amounts. Taxpayers should complete Part III, Form 1040X, where an explanation as to why the return is being amended can be given. If there is any change in the other schedules or forms, the new or updated schedules must be included with the amended filing.

When to file. If claiming an additional refund, taxpayers should file Form 1040X after receiving the refund from the originally filed return. Form 1040X should be filed within three years from the date the original return was filed, or within two years from the date the tax was paid, whichever is later.

If additional tax is owed, Form 1040X should be filed and the additional tax should be paid as soon as possible to limit interest and penalty charges.

Processing time. Normal processing time for amended returns is 8 to 12 weeks, assuming all the information needed to process the amended return is enclosed with Form 1040X.