You are correct. GF can file her own tax return and claim the children for the full amount of the child tax credit (assuming the children's other parent is not claiming them) even if she did not work in 2021. That means you cannot claim them at all, nor can you claim your GF, since dependents cannot receive the CTC.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
