The TT program fails to ask you when the SS# was issued so it may have allowed the credits that should not have been allowed. Your error was filing without the child on the original return then trying to amend the return to add the child and get the credits. A few years ago the IRS stopped allowing that as they point out in the notice and there is nothing you can do now to change the outcome. You should have waited for the SS# to be issued before filing the original return ... something a human tax pro would have told you to do but the DIY program doesn't warn you about.
