Do I need to complete the 2018 US Tax Return questionnaire before completing my Q1 2019 1040-ES? Another tax advisor already completed my 2018 US Tax Return.

[robtm]

If your tax advisor has completed your 2018 tax return, why do you need to complete it? Just send in what is already done. You can send in your 1040-es Q1 payment at anytime before or on 4/15. I don't know if there is a penalty for sending it in late. If there is, you can avoid it by sending in double what you owe on the Q2 6/15 payment.