You will need the printed/pdf version of your tax return. You are looking for Federal Information Worksheet. It will show the date if you selected one. Otherwise, the default date is the due date of the return. 07/15/20 this year.
Here is an article that will help you print/pdf your tax return.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"