With TurboTax Online you can only prepare one return in each account. You have to use a separate account for each return. You can only have 5 accounts with the same email address.
To prepare multiple returns you should use the CD/Download TurboTax software that you install on your Windows or Mac computer. You can prepare as many returns as you want. The IRS allows you to e-file a maximum of 5 federal returns and the associated state returns. You would have to file a 6th return by mail.
If you are accustomed to professional tax software, you will also be much happier with the CD/Download software. It allows you to see the forms while you are working on the return, it has features to easily trace the supporting form, schedule, or worksheet for an entry, and has other capabilities that are not in TurboTax Online.
