Under the Tax Cuts and Jobs Act, a child must have a valid Social Security Number to qualify for the Child Tax Credit. You cannot claim the credit for a dependent with an ITIN on either the original or an amended tax return.
What if my dependents don't qualify for the Child Tax Credit?
The Tax Cuts and Jobs Act introduced a new, nonrefundable Family Tax Credit of $500 for dependents who are not qualifying children. This includes children over 17, dependents with an ITIN, the elderly and the disabled.