Client went to a new preparer this year, they filed an extension for her (not sorry to see her go, she lives far from me and claims to be sick and dying and every year its huge crying dramatic scene) but is now claiming that the basis for deprecation on her rental that she bought back in 2006 is not right.

I didn't have her as a client until 2014 or 2015, so I have no clue how the basis was determined.  She was a client of my boss that retired, he had her for a client since the late 80's I think.

I did make an error on basis for a new rental she bought in 2016 (I failed to account for the land value!) I fixed them and sent her amended returns for 2016 & 2017 for those errors.

Client wants me to fix this 2006 error in basis....isn't this something her new preparer can do on the current year return with the 3115?  or how does this get fixed?

Her last email to me threatened me with an attorney for this 2006 basis error and making the mistakes in 2016 and 2017....I feel like I've corrected my mistake to the best of my ability told her Id cover any penalties related to those mistakes I amended for, and have no intention of helping her any further at this point, but for my own curiosity, how would you fix that 2006 basis error?