your husbands's income results in two types of taxes reported on the joint return. additional income taxes on the income and self-employment taxes. estimated taxes need to be paid for both types unless your withholding will cover his taxes. you might want to use Turbo tax's taxcaster to estimate your combines taxes for 2019
https://turbotax.intuit.com/tax-tools/calculators/taxcaster/
25% of estimated taxes for 2019 were due on each of these dates - 4/15/19, 6/15/19 and 9/15/19 with the final installment due 1/15/2020 . so if you use taxcaster, 75% of the estimated amount owed were due on or before 9/15.
when using taxcaster use estimated full year amounts.
