@ThomasM125 wrote:
Form 3115 is used for a change in accounting method. It is used when associated with a rental to correct depreciation that was not deducted properly in previous years.
It may be easier to use it once than to amend three years of tax returns.
There is no choice, actually. If the same impermissible method of determining depreciation was used in two or more consecutively filed tax returns, the only option would be to file Form 3115; amending three years of returns would not be allowed.
See https://www.irs.gov/publications/p946#en_US_2019_publink1000107385
