You should select this option to export all or some of the returns you had worked on during a certain period:
Enter a date range. The default date range is derived from the Tax Preparation Audit Trail.
Click OK. The Tax Return Preparation Audit Trail is interrogated for returns that have been changed during the period specified are ticked and to be included in export file.
For example, You have made changes to 100 returns, 15 of which were done in the last 2 days. If you set the date range to this 2 day period then the 15 returns will be exported.
If you delete, for any reason, your Tax Preparation Audit Trail no comparison will be possible.