Online is only good for 1 return per account. But you can use the same email address for 5 accounts. How to start another return in the Online version
No. You will have to create a new account with a new User ID to start another tax return using the TurboTax online editions - https://turbotax.intuit.com/personal-taxes/online/
The TurboTax online editions can only be used for one tax return per account and User ID. You can have up to 5 User ID's associated with one email address.