Is there an option to lock an individual T1 file with a password?
Your safest option is to create an encrypted folder on your hard drive and store the private tax returns in there. This provides a higher level of encryption, which you can also recover if you lose the password (assuming you are following the windows guidelines). In addition, these files will be hidden from Client Manager so none of the details will be shared with others in your office.
I use a windows server and index the secure directories so they show up on the client manager; however, if someone tries to load the file who does not have access to the secure directory, nothing happens. When I do it, it loads nicely since I have access to the directory