i don't see anything on the IRS website about what they do in this situation. so it is not known if they will automatically send you the CTC. trying to contact the IRS and get an answer is probably a waste of time because you may not get the right answer. see what others post. but unless someone posts for sure that you'll get it without filing an amended return, I would recommend filing it. however, to properly do this you first have to eliminate the CTC on line 28 because column A of the 1040-X is supposed to be as last file or last adjusted by the IRS. they changed line 28 to zero so that's where you need to start. it may be possible to do this by entering that you actually received the amount on line 28 so the return shows zero (form 8812 line 14i will show zero). then close the return and open it to amend this time eliminating the amount entered as received. line 28 should be back to what was originally filed.
you'll need to include an explanation which would include that you're amending to claim the CTC which was previously denied because your ex (name and SSN) got the advance. he repaid it because he was not entitled to claim the child.
