@Carl wrote:
Your 3 year time to amend your 2016 tax return ends on July 15th, 2019. After that date, amending will not be an option. You'll have to just include IRS Form 3115 with your 2019 tax return to correctly "fix" this.
The taxpayer actually has to file Form 3115 to rectify this situation because the taxpayer used the same impermissible method of determining depreciation in two or more consecutively filed tax returns.
See https://www.irs.gov/publications/p946#en_US_2019_publink1000107385
In short, amending is not an option.
