If you have already e-filed your tax return and it has been "Accepted" by the IRS, you will need to wait until you have received your refund, if applicable. Then, you will need to amend your return to make changes. You will need to send in any forms that caused the need for an amendment, such as a copy of birth certificate or social security card with a note stating your son's name was misspelled. You will also send the original 1040 Form, new 1040X Form. You will need to print, sign, date and mail your forms to the IRS.
If you have NOT already filed your tax return or if it gets "Rejected", please follow these instructions to update your son's name:
Please Note: If your return is "Rejected" you can make the change without having to amend your tax return.
We changed our son's last name last spring to reflect his biological father's last name. Turbo Tax is rejecting this change so we cannot efile. How do I fix this?
The reject may indicate that the file used by the IRS to match Social Security numbers and names has not been updated with your son's name change.
Be sure that the Social Security Administration was notified of the change.
You could attempt to file your return with his former name to see if the return will go through that way.
Also, check the reject code that you are seeing and carefully follow any instructions you have received from TurboTax with regard to fixing the issues. Just be sure that the name change is the root cause and not something else.