To do your return for you? Or to do their own return? NO, not to do their return.
The Online version is only good for 1 return. But you can use the same email address for 5 accounts. To do another return log out of your account and set up a new account and new user name and pay any fees again. That's why it's better to use the Desktop CD/Download program. The Desktop program can do more than 1 return and efile 5 for free.
How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...