The money you hear about people getting for just filing a tax return claiming kids requires them to have some earned income (wages or self employment). Without earned income, they are not eligible for the "refundable" Earned Income Credit or Additional Child Tax Credit. Both credits are calculated on the amount of earned income you have. No earned income means no "refund". A small amount of earned income means a small refund. The child tax credit does not "kick in" unless you have at least $2500 of earned income. SSI is neither taxable or reportable and is not earned income.
A child can be the “qualifying child” dependent of any close relative in the household. If you live another related person (parent, sibling, aunt, adult child, but not cousin) someone else, e.g. your parents, it may be better if they claim your child. The relative must be older than the child.
Instead, you could allow the non-custodial parent to claim the children. Non-custodial parents are allowed to claim the child tax credit, but not the Earned income credit.
If you are a student, over age 23, and are not claimed as a dependent by someone else (e.g. your parent) you may be eligible for the up to $1000 refundable American Opportunity (tuition) Credit. That credit is not dependent on having either kids or earned income. You must be at least a half time undergraduate student .
THIS ANSWER DOES NOT APPLY TO 2021 RETURNS. FOR 2021, THE CHILD TAX CREDIT IS FULLY REFUNDABLE, EVEN IF YOU DO NOT HAVE EARNED INCOME.
