even if you had a $1,000,000 tax liability with no withholding on January 1, 2019, the IRS does not require full payment of taxes on that date. you could pay 1/4 on each installment date 4/15, 6/15, 9/15 and 1/15/2020 and would incur no penalty.
on the other had say your entire liability occurred on 12/31/2019 with no withholding , your estimated tax payment of what's due wouldn't be required until 1/15/2020.
you would prepare form 2210 for 2019 using annualized income method showing all income earned in final period. along with tax payment, again there would be no penalty.
