You cannot claim them as "Qualified Child" dependents for the EIC or Child Tax Credit because they are not *your* children and you are not married.
You can only claim them under the "Qualifying Relative" (or other non-related dependent) of you meet the requirements. That will give the the $500 other dependent credit and nothing else.
In TurboTax you must enter them as "Other person", NOT your child.
The "proof" they want is a copy of the child's birth certificate with your name on it and/or a copy of your marriage certificate to show that you are the step father.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
