"Attach the original Form 3115 to the filer's timely filed (including extensions) federal income tax return for the year of change. The original Form 3115 attachment does not need to be signed. File a copy of the signed Form 3115 to the address provided in the address chart on this page, no earlier than the first day of the year of change and no later than the date the original is filed with the federal income tax return for the year of change. This signed Form 3115 may be a photocopy."
Source: page 2 of instructions https://www.irs.gov/pub/irs-pdf/i3115.pdf
Form 3115 is not available in TurboTax Online. It is only available in the CD or download TurboTax software, and can only be completed in forms mode. There is no support for it in the Step-by-Step interview.
