In your tax report, if you haven't already, please select form 2074. The following calculator will help you determine how you should fill it out for ESPP sales. For each sale, you will have to fill a new section of the form (fields 512, 514, 515, 520, 521 and 524). Once you've filled out the form for all sale events, field 3VG should be pre-filled with your total adjusted gain / loss (in euros).

For ETrade users, the name of the inputs below should match the columns in your "Gains and Losses" spreadsheet. You can download that Spreadsheet in the Gains and Losses page after selecting your tax year and clicking "Download" and "Download Expanded".