不是的，你理解有误。 building的initial cost basis 不是每年变。

你在第一年报renal SCH E时，就把房子的折旧要用到的 original cost basis 定好了，不是按政府每年变化的估价从新定。 按照你现在房子的估价，算出building占多少 %，比如占80%， 那你房子用来折旧的 cost basis = 200，000 x 80% = 160,000. This is your building cost basis for depreciation calculation. If you rent it from 1/1/11 to 12/31/11 for the whole year, your 2011 depreciation expense fro Sch E deduction = 160,000/27.5 = 5819/year (using straight line method)  If you only rent it for a few months, for example only 7 months in 2011， your 2011 depreciation expense = 5819/12x7 months. 我看你还是好好琢磨一下关于出租房的报税表和instruction 吧。要不找CPA firm 帮你报税好了。