You can only file one tax return per TurboTax Online account. You can set up to 5 accounts per email address and each account has a unique User ID. But, you get one return per fee. .
When you use Desktop TurboTax, which you install from a CD or download to your own hard drive, you can prepare and e-file multiple returns for the cost of the software. You can e-file up to 5 Federal returns. If you have multiple returns to prepare , Desktop is more cost effective.
Here is additional information on the CD/Download Products: https://turbotax.intuit.com/personal-taxes/cd-download/
