If you made a mistake when filing your return, you will file an amended return (Form 1040-X) to report the additional information.
The article below has specific amendment instructions for 2016:
When you have prepared your amended return and are ready to mail Form 1040-X you should include the following forms:
- Form 1040-X
- The new (amended) Form 1040
- Any forms or schedules that were added or changed as a result of preparing the amendment
Please note that 1040-X cannot be e-filed - you will need to mail a paper return. It takes the IRS at least 2 - 3 months (and sometime up to 6 months) to process amended returns. Also, depending on whether the changes affect your numbers, you may also be required to file an amended return with your state.
