OK ... if they denied the CTC did they also deny the dependent ? Did you not enter the correct advance CTC payment when asked?
To amend the return you will have to make the same corrections the IRS did ... that must be the amounts on Column A of the 1040X. You can either fill in the 1040X manually or go back thru the interview BEFORE you start the amendment process and answer the questions in such a way that the return will reflect the IRS changes. Once the return is as the IRS has it only then can you start the amendment process.
I GOT A LETTER FROM THE IRS
https://ttlc.intuit.com/questions/3605673-i-got-a-letter-or-notice-from-the-irs
I AM BEING AUDITED
If you purchased Audit Defense:
https://ttlc.intuit.com/questions/2924451-i-bought-max-or-audit-defense-and-now-i-m-being-audited
AUDIT SUPPORT
https://support.turbotax.intuit.com/irs-notice/audit-support/
