Investors & landlords

@Carl thanks, my tax preparer friend was depreciating both of my foreign properties at 27.5 years 😢😩.  One was placed in service in 2006 (should be 40 years) and the other in 2020 (should be 30 years).  Should I:

1.  amend prior years returns (up to how many years?), or

2.  is form 3115 used for this type of error?  

Or any other advise?  Thanks in advance..

R…