In TurboTax Online, you can prepare and e-file one federal and up to five associated state returns under the same login.
You can also e-file up to five federal returns for each email address tied to a TurboTax account, but you must create a separate login for each return, and each return should have a unique Social Security or Tax ID number.
The IRS prohibits using the same email address to e-file more than five federal returns with an online personal tax return preparation product.
Please read this TurboTax FAQ for information on: "How do I start another return in TurboTax Online?": How do I start another return in TurboTax Online?