A client purchased residential rental property in 2018 and did not depreciate it on his tax returns for years 2018 and 2019.  It looks as though I need to file Form 3115 Application for Change in Accounting Method as he went from an impermissible accounting method (not depreciating the property at all) to a permissible accounting method (MACRS). I (think) I filled out 3115 properly. 

Adding to my confusion is the Section 418(a) adjustment . It is asking for the adjustment, negative or positive, to income. Would I simply input the depreciation he missed out on for the last 2 years?  It seems that my tax software has already played catchup on the missed depreciation and will average it out over the remaining life which would effectively create a double dip if I also include it as a 481(a) adjustment.

Thank you, 

Lost but Hopeful