You actually have 2 problems to deal with.
First, If you have already e-filed the child's return DO NOT DO ANYTHING until it is accepted. Then, it is BEST TO WAIT until the refund is actually received.
Then you can prepare an amended return form 1040-X the change the designation that the child can be claimed by someone else. An amended return MUST be PRINTED and MAILED --it can take up to 2-4 months for an amended return to be process by the IRS.
Perhaps some terminology/definitions would be in order:
AMEND:- your return is what you do AFTER your return has been filed and accepted
by the IRS and/or state. (No additional charge)
CHANGE:- your return is what you do BEFORE your return has been filed --simply go
back to the respective information and change it as needed.
CORRECT:- your return is what you do AFTER you attempted to file your return and
it is rejected by either IRS, or state --again, simply go back to the
respective information and change it as needed.
Above all DO NOT DO ANYTHING until you find out if your return is rejected or accepted.
Second, since it could take take up to 4 months for the IRS to process the child's amended return, and then another 30+ days to update the SSN database info, your only option this year is to NOT e-file and PRINT and MAIL your own return.
It might also be a good idea to actually take your PRINTED return and the amended return, form 1040-X, to the Post Office and mail it 'Certified' with 'Return receipt requested'. That way you'll have actual proof that the IRS did receive it and when.
NOTE: When mailing your tax return(s) NEVER put more than one return in an envelope, if you put more than one return in the envelope there is a good chance that they will be treated as a single return and thus delay any action.
