As Patricia mentioned, the 3115 isn't available in TurboTax online, but you can fill out the 3115 form in TurboTax Desktop if you switch to forms mode. But that will still not likely be adequate since the 3115 has some required statements that you need to attach to it for most types of depreciation changes, and TurboTax doesn't provide a way to attach these required statements to your e-filed tax return. You could instead paper file your tax return and add the additional statements that way. But another option is you can e-file your tax return, and then within 3 business days, mail in the 3115 along with IRS form 8453 that can be used to provide a paper 3115 form separately from your e-filed tax return.
By the way, you do additionally still need to also mail another copy of the 3115 to the IRS at a different mailing address, as explained in the 3115 form instructions.
The 3115 form and the required statements is a complicated process to figure out. If you search online video websites, you should be able to find tutorial videos that should help explain how to file form 3115, and possibly information on specifically how to do that if you're using TurboTax for the rest of your tax return.
David O
