My son turned 18 on January last. He opened his own account in US dollars (here in Chile) as instructed by the SSA. I have transferred to his account all the money I collected and conserved for him during all these years. Is this correct? Do I have to inform the SSA? Thank you for your advice
Technically, no. What you should have done instead is return the conserved funds to Social Security so that they could then reissue them to your son (https://secure.ssa.gov/apps10/poms.nsf/lnx/0200603055).
You should probably check with Social Security at this point to determine how they want you to handle the situation. They may simply go ahead and authorize the direct transfer retroactively, but it's probably best to leave it up to them.