Cost basis on property that was gifted, and then completed a 1031

[Alissa S.]

I’m trying to estimate the amount I will owe on the sale of 11 units.

During my childhood, I was gifted approx $150k in property value from my grandparents between 1997-2001. They died in 2007 and then 2013, and the property continued to appreciate. We used that value to complete a 1031 exchange in 2016, when I was adult (if that matters). I bought approx 10% share in 11 MFR units, and we are now selling them.

Is my cost basis the basis at original gift, or the basis at 1031 exchange? How is the basis calculated if the value was gifted over a series of several years?