綁定了以後就不能分開了，賣一個房子可以用所有的loss carryover抵稅。

下麵這個節選分析了你可以根據你自己的情況分割合並計算自己的生意，比如按類型，按地區，或者都合在一起。

自己看一下，不懂再來問。

 

https://www.irs.gov/instructions/i8582

 

Grouping of Activities

Generally, one or more trade or business activities or rental activities may be treated as a single activity if the activities make up an appropriate economic unit for the measurement of gain or loss under the passive activity rules.

Whether activities make up an appropriate economic unit depends on all the relevant facts and circumstances. The factors given the greatest weight in determining whether activities make up an appropriate economic unit are:

1. Similarities and differences in types of trades or businesses,

2. The extent of common control,

3. The extent of common ownership,

4. Geographical location, and

5. Interdependencies between or among the activities.

 

Example.

 

You have a significant ownership interest in a bakery and a movie theater in Baltimore and in a bakery and a movie theater in Philadelphia. Depending on all the relevant facts and circumstances, there may be more than one reasonable method for grouping your activities. For instance, the following groupings may or may not be permissible.

• A single activity.

• A movie theater activity and a bakery activity.

• A Baltimore activity and a Philadelphia activity.

• Four separate activities.

 

Once you choose a grouping under these rules, you must continue using that grouping in later tax years unless it’s determined that the original grouping was clearly inappropriate or a material change in the facts and circumstances makes it clearly inappropriate.

 

The IRS may regroup your activities if your grouping fails to reflect one or more appropriate economic units and one of the primary purposes of your grouping is to avoid the passive activity limitations.