here's an answer I found. it makes since there is no guarantee you'll sell the house.
see if others have a different answer.
If you sell such vacant land before you sell the home it surrounds, the sale will not qualify for the capital gains tax exclusion at that time. But, if you sell your main home within two years after you sold the vacant land, the prior sale will come within the exclusion. In this event, you may amend your return for the prior year and get a tax refund.
