@Carl wrote:
The 3115 would be used only if you are past the 3-year statute of limitations.
Form 3115 would be used if the treatment of a material item is done in the same way on two or more consecutively filed federal income tax returns.
See Rev. Proc. 2015-13
An example with respect to depreciation would be if the taxpayer filed a 2017 and 2018 federal income tax return without any allowance for depreciation. In that instance, a Form 3115 would be required; amending would not be allowed.
