Cost Basis For Stock Sale

[Westward221]

I am helping a family member file her taxes. She has a stock sale with no basis value and no way of determining it. She had a similar situation previously, and her tax preparer determined a ten year average value for the basis value of the stock. Is this an acceptable method for determining basis, or should I use another method?

[fanfare]

did she sell the same stock?

Use the same basis value again this year.

[Westward221]

No it is a different stock.