@DavidD66
Good point, I missed that.
@johnm40
From your question,
"My mom gifted a piece of property to me that has been in our family for over 50 years. I "believe" the property was gifted to her and my dad from my grandparents."
There is likely one part of the basis you can prove. If your mother and father owned the property together, and your father died before your mother gave you the property, then your basis is half the fair market value on the day your father died.
Basically, we start with the provable basis (zero). But then when your father died, your mother got his "half" of the property with a stepped up basis equal to half the fair market value on that day. And if your parents lived in a community property state, your mother got a fully stepped up basis. You can determine the FMV on the date your father died by talking to a real estate appraiser, they can look at historical records and give you an estimate. So your mother's half basis is still zero that you can prove, but the half-basis she inherited when your father died is something you probably can prove. All this assuming they owned the house together when he died, of course. If she was divorced, or was only given the house by her parents after she was single, then we are back to square one.
