You will need to print, sign, and mail your tax return to the IRS. To
prevent fraudulent returns, the IRS will only accept each dependent's SSN once
in their e-file system. If another tax return has been
filed using the child's SSN, no further e-files using that SSN will
be accepted in the e-file system (even if they did not claim the child as a dependent but the child's SSN was on the tax return).