Investors & landlords

I don't think that qualifies for Form 3115.  It was just a math error, not a "method" error.  So the only thing you can do is amend the past few years.

 

As a side note, it was YOU that must have entered 52%.  You should have entered 100% in that first year because it was 100% business use STARTING with the date you "placed it in service".