Also be aware that Online Premium is not as fully-featured as desktop Premier. For example, if you are used to using Forms Mode in the desktop version for correcting any entries or troubleshooting, be aware that Online Turbotax does not have a Forms Mode, so you can't make any changes directly on a form. In Online TurboTax you can only view a few main forms during preparation (the 1040 and Schedules 1-3) and cannot print anything, unless you pay in advance to have full viewing/printing privileges of all forms.
The Online version can only prepare 1 Federal return per account, while the desktop version can prepare multiple Federal returns with up to 5 free Federal efiles. As a result, in the desktop version it's easy to run scenarios in test returns or to prepare returns for other family members, if applicable.
In the Online version, there is an extra fee to prepare a state return, while desktop Premier includes a state program that prepares multiple state returns (of that same one state.) There is a $20-25 fee to efile each state return in the desktop version (no efile fee for NY state), but there's no fee if you elect to postal mail the state returns.
