Following the Turbo Tax guide, I am using the investment section and property. The flow of questions requires entry of FMV of the property sold when it was acquired. The property was acquired thru inheritance. Only a small portion of the property is affected by the easement.
If you can determine what the FMV of the entire property was on the date you inherited it, you could allocate a % of that value to the easement, using total square footage of the property, and square footage of the easement.
A real estate appraiser may be needed, unless you have an Assessment Statement for the property.
This is probably the best way to do this, not having a value for the easement itself.
Here's some additional info from the IRS on the subject:
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