The IRS states that in event of gross (>$1000) tax underpayment, penalties are avoided if current years withholdings and refundable credit is more than last years total taxes.
Nowhere in their explanation do they indicate to which Form 1040 lines do "total taxes" or "withholding and refundable credits" correlate, but I assume what they mean is that if, in Form 1040 , the value in line 74 (aka "total payments") of the current year is greater than value in line 63 (aka "total taxes") of the previous year, you are exempt from underpayment penalties.
First, am I correct in my understanding of this?
Second, now that Child Tax Credit is partially refundable for 2018, does it count towards the "refundable credit"? And if CTC does count towards "refundable credits" what is the applicable amount: $2000 or $1400 (refundable cap)?