Each return is in a separate data file. If they use the same computer they could open a retun unless you save it with a password.
There is the Desktop CD/Download program and the Online browser version.
The Online versions are only good for one return per account. And you may need to upgrade to a higher version to enter certain things. See the Online versions here, https://turbotax.intuit.com/personal-taxes/online/
All the Desktop versions have the same forms so you can use a lower version. You just get more help in the higher versions. You can see and buy the Desktop versions here, https://turbotax.intuit.com/personal-taxes/cd-download/
And the Desktop program can do unlimited returns and efile 5 Federal for free.
You can see and enter directly into the actual forms.
There is a What-If worksheet.
Basic does not include a free state program and has some other limitations like doesn’t import from It’s Deductible.
Deluxe and above include one free state program download to prepare unlimited returns for the same state. Then each state return is $20 to efile (goes up to $25 in March). Or you can print and mail state for free. If you need to also file a state return for a different state it is $40 to buy an additional state program.
If you buy Deluxe in the stores it comes 2 ways, Deluxe with State and without state for states that don't have an income tax. So watch what you buy. It should say Federal+Efile+State.
