Under pre-TCJA law, the child tax credit was $1,000 per qualifying child, but it was reduced for married couples filing jointly by $50 for every $1,000 (or part of $1,000) by which their Adjusted Gross Income (AGI) exceeded $110,000. (The threshold was $55,000 for married couples filing separately and $75,000 for unmarried taxpayers.) Starting in 2018, [...]