Just had an idea, and here's how I recommend you do this.
Work this through the Rental & Royalty Income (SCH E) section of the program "as if" you are renting out everything, including the barn. On this initial work through, you'll be treating the house and barn as a single structure. So when asked, you'll enter the following:
COST: what you paid for the property in it's entirely. Let's assume $200,000
Cost Of Land: Of that $200,000, lets say $50,000 was for the land.
With the above, once you complete working this through the rental section, your deprecation will be figured on $150,000 over 27.5 years. (Remember, land is not depreciable).
Now, go back into the Assets/Deprecation section and lets make some changes. We know, using my figures above, that the value of all structures on the land is $150,000. Let's give the house you are renting out a value of $100,000 and the barn a value of $50,000. Then we'll give the value of the land for the barn a value of $15,000 and the value of the land for the house a value of $35,000.
Select the "Enter Another Asset" button and enter the house with a cost of $135.000 (cost of house and land) and Cost of Land a value of $35,000. We'll declare this 100% business use.
Now enter a 2nd asset of the barn with a cost of $65,000 and Cost of Land $15,000. We'll give this ZERO percent business use.
Now you can delete the first asset which includes everything, and depreciation will occur only on the house. In later years if you decide to rent out the barn, it's just a matter of changing the percentage of business use, placing it "in service" with the appropriate in service date, and that will begin depreciation on the barn.
