Is 2019 tax liability used for form 2210 the amount of taxes owed (1040 line 24), or $0 if I paid all my 2019 taxes on time?

[ssolfest]

current online answer is confusing as it states it is taxable income less some credits but then states is it 1040 line 24 which is total owed after payments

[JoannaB2]

No.  The form 1040 line 24 is your total tax for 2020 income tax return.  If you don't have liability or paid it off in 2019, skip the line or enter zero. 

The form 2210 is used to report underpayment of estimated tax by individuals, estates, and trusts. If you didn't check box B, C, or D in Part II,t he IRS will figure any penalty for underpayment of estimated tax and send you a bill. 

Generally, you may owe the penalty for 2020 if the total of your withholding and timely estimated tax payments didn't equal at least the smaller of 90% of your 2020 tax, or

100% of your 2019 tax. Your 2019 tax return must cover a 12-month period.

[ssolfest]

I clarified with specialist that when determining is I had a 2019 tax liability, the number should be what was owed at the time I completed the 2019 taxes.   thanks