你没有想过卖A和卖B是不是同一年的。
比方说买股票,只要卖得多过买的,你就可能要交税,但是可以用同一年的损失抵掉,不考虑carry over.
房子有些不同,不能肯定卖房子的盈利和passive income是否可以抵掉。也许不能。因此,你先卖赚的钱要交税,后来卖房子亏得钱多半得carry over到未来。I could be wrong, but it might depends on many factors. Base rule is simple: paying tax is always easier than get them back!
Read this one: http://turbotax.intuit.com/tax-tools/tax-tips/Rental-Property/Selling-Rental-Real-Estate-at-a-Loss/INF12125.html
http://www.irs.gov/pub/irs-pdf/f4797.pdf