2015 I underestimated the cost of my property that I inherited from mom (JT), which was rented. Want to change original cost in 2016 but calc doesn't work. How to fix?

[dilbertw]

I tried to change the original cost for the rental property but not calculating correctly.  Used deprec of MACRS 27.5 years midseason.  2015 was correct. On top of calculating correct depr for 2016, I also want to adjust for understatement of depreciation in 2015.

[Rick19744 · Accepted solution]

The technically correct way to do this is to amend your 2015 tax return.

The other option, much more complicated, is to prepare a form 3115 for the automatic change in accounting for this error. 

The third option would be to add this additional cost basis to your 2016 detail, show it as placed in service in 2015, reflect the correct amount of 2015 depreciation that was not taken, and then TT will compute the correct 2016 depreciation.  Here you avoid amending, avoid preparing a form 3115, but you do forgo the lost depreciation.  You have to weigh the cost of amending versus the lost depreciation.