If you have selected the option Lock client data file after EF acceptance at Setup > Options > EF, when you attempt to open a return that has been e-filed and accepted, you see a warning message with Yes, No, and Cancel options:

If you click Yes to proceed, the return opens normally (unless the preparer has restricted security settings enabled).

When the option Lock client data file after EF acceptance is set, a preparer opening an accepted return can view it and enter data if the preparer's security rights permit it. The displayed message serves only as a warning.

A preparer who has limited security rights will see a slightly different message when attempting to open an accepted return. If they click to open the return, they will see gray data entries fields that are "read only."

Locked accepted returns can also be opened by going to Tools > File Maintenance > Unlock Client Files. This does not eliminate the warning message or change the locked status of a return. It simply opens the return to the warning message. A preparer with inadequate security will not have access to that menu.