For safe harbor, I understand that I need to make 4 equal estimated tax payments plus my W2 withholdings that in total are at least 110% of "last year's tax". I am unclear which line on last year's 1040 indicates that amount.
So I am clear how to cover safe harbor. 110% of last year's tax owed divided into 4 equal payments, or do I include tax withholdings from my paycheck and if so which pieces of those tax withholdings are included in the safe harbor calculation?
