The Biden administration wants families with children to know that there is roughly $193 billion waiting for them — all they need to do is file their taxes to claim it.

That estimated total is what remains of the expanded child tax credit, and the administration is concerned that some of those most in need of the assistance may be the least likely to get what is due to them.

President Joe Biden increased the payments and expanded who was eligible as part of his coronavirus relief package. While most families already received half of the credit as monthly payments last year, they'll lose out on...