The increase in the Child Tax Credit will take effect on your 2018 tax return you will prepare in 2019.
For families with children the Child Tax Credit is doubled from $1,000 per child (2017) to $2,000. In addition, the amount that is refundable grows from $1,100 to $1,400. The bill also adds a new, non-refundable credit of $500 for dependents other than children. Finally, it raises the income threshold at which these benefits phase out from $110,000 for a married couple to $400,000.
See Tax Reform: We’ve got you covered
https://turbotax.intuit.com/tax-reform
