If you have a child under the age of 17, you may be eligible for a $2,000 tax credit, $1,400 of which is refundable (payable even if more than the tax you owe). The child tax credit in 2018 is double what it used to be. You can take the credit for each eligible child.
Also, the income limits on eligibility have been dramatically increased — $400,000 for joint filers and $200,000 for other filers. This means more individuals are eligible to claim the credit.
And there’s a new child tax credit of up to $500 for other dependents who are not your qualifying child (e.g., a disabled child of yours who is age 22 and lives with you). This credit is not refundable but cuts your tax bill dollar-for-dollar.