Since the children are not your biological children and you are not married to the mother of the children you are not eligible for the Child Tax Credit on your tax return.
You can claim the children as your dependents and the mother of the children as a dependent under the Qualifying Relative rules where you may be eligible for the Other Dependent credit of $500 for each dependent. Provided that they meet all the rules for a Qualifying Relative.
To be a Qualifying Relative -
1. The person cannot be your qualifying child or the qualifying child of any other taxpayer. A child is not the qualifying child of any other taxpayer if the child's parent (or any other person for whom the child is defined as a qualifying child) is not required to file an income tax return or files an income tax return only to get a refund on income tax withheld.
2. The person either (a) must be related to you or (b) must live with you all year as a member of your household.
3. The person's gross income for the year must be less than $4,400 (social security does not count) in 2022
4. You must provide more than half of the person's total support for the year.
5. The person must be a U.S. citizen or a U.S., Canada, or Mexico resident for some part of the year.
6. The person must not file a joint return with their spouse.
