在房子交割的那一天，回头看五年，必须满足自住2+yr 才能免税 of $250K gain

如果你在过去的5年内，在盖房子住的少于24个月，那么你的Gain 就必须在income tax 里保税。 但是有特例：

Exceptions to the 2 out of 5 Year Rule

If you lived in your home less than 24 months, you may be able to exclude a portion of the gain. Exceptions are allowed if you sold your house because the location of your job changed, because of health concerns, or for some other unforeseen circumstance.