@KNERD
<<For clarity, you are saying there a dependent credit of $500 for each one, then a separate Child Tax Credit (the one the IRS is denying)? >>
there are TWO tax credits and it's an "either or" situation.
1) everyone listed as a dependent on your tax return is eligible for up to $500 as an 'other dependent tax credit". However, it is what is called a 'non-refundable tax credit". You must have tax liability on Line 18 to be eligible for it. Then the tax on line 18 gets reduced by $500 per dependent (but the result can't go below zero hence "up to"). If you don't have any liability on Line 18, you are not eligible for it. (In 2019 the 'tax liability' line is 12a; in 2020 the tax liability line is 16, in 2021-2022, the tax liability line is 18).
2) BUT! for children under the age of 17, there is a different tax credit. worth up to $2000. To be eligible for it is more complicated. You must have earned at least $2500 or have tax liability on the lines noted in #1. Depending on your earning or your tax liability determined how much of the $2000 you can get. For 2021 ONLY, the rules were quite simple and different: children ages 0-5 were worth a $3600 credit and children 6-17 were worth a $3000 credit. (note that the tax credit is for children UNDER the age of 17, but in 2021 ONLY it INCLUDED children that were age 17)
Most take tax credit #2 for their children, but if there is a circumstance where they are not elgiible for #2 (and your social security issue creates that for 2019), you can take tax credit #1.
