I sold .3 acres of 7.5 acre property as a boundary line adjustment transaction....how do I report that....

Find the Cost Basis of the entire piece of land, and calculate the .3 acre Cost Basis. 

 

Cost Basis is original purchase price, plus improvements, less any depreciation taken.  

 

Any gain would be calculated on Net Sale Proceeds, less Cost Basis and Sales Expenses. 

 

Click this link for more info on Reporting a Land Sale.