If you already filed your return before receiving the additional form, you will file an amended return (Form 1040-X) to report the additional information.
Note: You will most likely still receive the original refund that you claimed.
You will need to wait until your original tax return is processed by the IRS before filing an amended return. If you are receiving a refund, you should wait until the check is issued or you receive your direct deposit.
You should not have any problems or penalties assessed to you if you file the amended return and pay any taxes owed by April 18, 2017.
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:
- 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.
