There is no charge to e-file your return in TurboTax Online. The charge is to prepare your return in TurboTax Online regardless if you e-file or print and mail your return in. There are some users who do not have to prepare and file a state return if the state you live in doesn't have income tax. Here's more info if this is the case:
https://ttlc.intuit.com/replies/3302048
