When using the online product, two people cannot access tax prep at the same time on the same account. The account can only be open on one computer at a time. If one person logs off the account, then another person can log on. 

If two people are trying to prepare two different tax returns, each person must have their own account. Each account can only be used to prepare one tax return.

When using the CD/download product, the tax return is only one one computer. It cannot be accessed from any other computer without moving the .tax file to the other computer and having the program installed on the other computer.